Doug's Headers - D521-B

Doug's Headers D521-B 1 3/4" 4-Tube Full Length Header Pontiac Catalina 326-455 65-68 Hi-Temp Black Coating

Doug's Headers D521-B 1 3/4" 4-Tube Full Length Header Pontiac Catalina 326-455 65-68 Hi-Temp Black Coating

Part Number: D521-B / UPC 694342543587
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Product Info

  • 3/8" Thick machined flanges...no warping
  • CNC mandrel bent tubes... accurate fit & better flow
  • Precision formed long transition collectors and long tube design... reduces backpressure and increases higher RPM horsepower
  • Heavy 16 gauge tubing...longer life
  • Tubes are pre-polished to remove scratches and the header is finished with a Hi-Temp Black Coating

 

 

Applications and Footnotes

Pontiac - Bonneville, Catalina

    EMISSION       AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

    EMISSION       AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

 

 

Applications and Footnotes

Pontiac - Bonneville, Catalina

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

 

 

Key for abbreviations and acronyms
2V Two valve cylinder head
DP Dual Smog Pump (emissions device)
PSIG Pounds Per Square Inch Gauge
3V Three valve cylinder head
E.O. Executive Order
RD Round Port
4V Four valve cylinder head
EGR Exhaust Gas Recirculation (emissions device)
REC Rectangle Port
A/C Air Conditioning
FLR Floor
SAP Same As (cylinder head) Port
AUTO Automatice Transmission
MCTBC Metallic Ceramic Thermal Barrier Coating
SP Single Smog Pump (emissions device)
COL Column shift
OVL Oval Port
STD Standard Transmission
COLL Collector
P/B Power Brakes
T.P.I. Tuned Port Injection
DIA Diameter
P/S Power Steering

 

 

Highlights

  • 3/8" Thick machined flanges...no warping
  • CNC mandrel bent tubes... accurate fit & better flow
  • Precision formed long transition collectors and long tube design... reduces backpressure and increases higher RPM horsepower
  • Heavy 16 gauge tubing...longer life
  • Tubes are pre-polished to remove scratches and the header is finished with a Hi-Temp Black Coating

Applications and Footnotes

Pontiac - Bonneville, Catalina

EMISSION AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

EMISSION AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Applications and Footnotes

Pontiac - Bonneville, Catalina

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Key for abbreviations and acronyms
2V Two valve cylinder head
DP Dual Smog Pump (emissions device)
PSIG Pounds Per Square Inch Gauge
3V Three valve cylinder head
E.O. Executive Order
RD Round Port
4V Four valve cylinder head
EGR Exhaust Gas Recirculation (emissions device)
REC Rectangle Port
A/C Air Conditioning
FLR Floor
SAP Same As (cylinder head) Port
AUTO Automatice Transmission
MCTBC Metallic Ceramic Thermal Barrier Coating
SP Single Smog Pump (emissions device)
COL Column shift
OVL Oval Port
STD Standard Transmission
COLL Collector
P/B Power Brakes
T.P.I. Tuned Port Injection
DIA Diameter
P/S Power Steering

Emissions Code Key

The application guide above specifies which Emissions Code applies to this part. Doug's Headers uses a voluntary product identification program whereby all mission-sensitive products can be identified by placing numbered labels in product packaging and listing corresponding numeric codes next to each part number. The corresponding numbers and explanations are as follows:

This Product has been granted a California Air Resources Board (CARB) "E.O" (Executive Order) Exemption, or is considered a Direct Replacement or Consolidated Replacement part. It is 50 State Legal when installed on the appropriate vehicle per the Manufacturer Application guide and Installation Instructions

This product is Legal for use on 1974 and older non catalyst equipped vehicles and is considered a "replacement part" per California Air Resources Board regulations, as long as ALL emissions sensitive components are retained, including A.I.R., EGR, Heat Risers etc. Failure to retain any of these components, or use on any 1975 or newer catalytic converter equipped car would render this product Illegal for Street or Off Highway Use in California, or in states that have adopted California Emissions regulations and may only be used for Closed Course Competition.

This product is Not legal for Street or Off Highway use in California or in states that have adopted California Emissions Regulations and is only intended for Closed Course Competition use, except 1965 and Older US manufactured California Certified vehicles, 1967 or older US manufactured Federally Certified vehicles, or 1967 and older Foreign manufactured vehicles which may have any aftermarket add-on or modified part installed as long as the vehicle can still meet the tailpipe emission standards for the year of the vehicle and retain any original or retrofit crankcase control (PCV) devices and NOx device required for the year of the vehicle.

Additional Information

Doug's PASSENGER CAR HEADERS Long Tube Hi-Temp Black Coated Header development and design is complex and requires a substantial amount of time and resources to do the job right! Many manufacturers are unwilling to make the commitment and instead offer compromised headers at lower prices. Doug's will not compromise performance, quality or fit to compete with inferior designs at cheap prices. Every Doug's header is tuned with the proper tube size and length to efficiently remove all the exhaust from each cylinder, reducing pumping losses resulting in a dramatic increases in horsepower and torque. Doug's headers are carefully developed on the vehicles they are intended to fit and are re-checked numerous times during the design and manufacturing process.

Download instruction manual

Instruction Manual
Instruction Manual

Download PDF

Shipping & Delivery

Our ignition and exhaust products ship from our warehouse in Lenexa, KS. Our normal shipping time is 2-3 working days when the part is in stock. Freight is FOB, Lenexa and all claims for shortages, damages, etc. must be filed by consignee.

All packages must be inspected upon receipt for any missing or damaged goods and claims for such must be made within 7 days of receipt. PerTronix does not currently ship our products internationally from our web store.

For international orders call 909-599-5955 or connect with us here.

Returns & Replacements

Returns at Pertronix are accepted within 90 days of purchase with prior authorization, ensuring items are in new, resalable condition. To initiate a return, call for an RGA and follow provided instructions. Customers are responsible for return shipping, using a trackable method.

Refunds exclude initial shipping and handling fees and may be subject to a restocking fee. For defective or damaged items, contact Pertronix directly. We are not responsible for user-initiated damage/loss of parts.

For complete details, visit our Returns page.

Reviews

Doug's Headers - D521-B

Doug's Headers D521-B 1 3/4" 4-Tube Full Length Header Pontiac Catalina 326-455 65-68 Hi-Temp Black Coating

Doug's Headers D521-B 1 3/4" 4-Tube Full Length Header Pontiac Catalina 326-455 65-68 Hi-Temp Black Coating

Part Number: D521-B / UPC 694342543587
Regular price $912.95
Sale price $912.95 Regular price

Shipping calculated at checkout.
Part Number: D521-B / UPC 694342543587
  • Free shipping on $99+ orders in lower 48 states
  • 90-day return policy
  • We’re here to help! Call us on 909-599-5955
Emissions code

Emissions Code

Continue Reading to Understand Emissions Codes

View full details

Product Info

  • 3/8" Thick machined flanges...no warping
  • CNC mandrel bent tubes... accurate fit & better flow
  • Precision formed long transition collectors and long tube design... reduces backpressure and increases higher RPM horsepower
  • Heavy 16 gauge tubing...longer life
  • Tubes are pre-polished to remove scratches and the header is finished with a Hi-Temp Black Coating

 

 

Applications and Footnotes

Pontiac - Bonneville, Catalina

    EMISSION       AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

    EMISSION       AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

 

 

Applications and Footnotes

Pontiac - Bonneville, Catalina

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

 

 

Key for abbreviations and acronyms
2V Two valve cylinder head
DP Dual Smog Pump (emissions device)
PSIG Pounds Per Square Inch Gauge
3V Three valve cylinder head
E.O. Executive Order
RD Round Port
4V Four valve cylinder head
EGR Exhaust Gas Recirculation (emissions device)
REC Rectangle Port
A/C Air Conditioning
FLR Floor
SAP Same As (cylinder head) Port
AUTO Automatice Transmission
MCTBC Metallic Ceramic Thermal Barrier Coating
SP Single Smog Pump (emissions device)
COL Column shift
OVL Oval Port
STD Standard Transmission
COLL Collector
P/B Power Brakes
T.P.I. Tuned Port Injection
DIA Diameter
P/S Power Steering

 

 

Highlights

  • 3/8" Thick machined flanges...no warping
  • CNC mandrel bent tubes... accurate fit & better flow
  • Precision formed long transition collectors and long tube design... reduces backpressure and increases higher RPM horsepower
  • Heavy 16 gauge tubing...longer life
  • Tubes are pre-polished to remove scratches and the header is finished with a Hi-Temp Black Coating

Applications and Footnotes

Pontiac - Bonneville, Catalina

EMISSION AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

EMISSION AUTO STD TUBE COLLECTOR PORT
YEARS ENGINES CODE A/C P/B P/S COL FLR COL FLR SIZE (in.) SIZE (in.) SHAPE
65 - 68 326-455 Y Y Y N Y N Y 1 3/4 3 D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Applications and Footnotes

Pontiac - Bonneville, Catalina

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Pontiac - Grand Prix

YEARS 65 - 68
ENGINES 326-455
EMISSION CODE
A/C Y
P/B Y
P/S Y
AUTO COL N
AUTO FLR Y
STD COL N
STD FLR Y
TUBE SIZE (in.) 1 3/4
COLLECTOR SIZE (in.) 3
PORT SHAPE D-Port
Requires removal or modification of locking steering columns if equipped
Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

Key for abbreviations and acronyms
2V Two valve cylinder head
DP Dual Smog Pump (emissions device)
PSIG Pounds Per Square Inch Gauge
3V Three valve cylinder head
E.O. Executive Order
RD Round Port
4V Four valve cylinder head
EGR Exhaust Gas Recirculation (emissions device)
REC Rectangle Port
A/C Air Conditioning
FLR Floor
SAP Same As (cylinder head) Port
AUTO Automatice Transmission
MCTBC Metallic Ceramic Thermal Barrier Coating
SP Single Smog Pump (emissions device)
COL Column shift
OVL Oval Port
STD Standard Transmission
COLL Collector
P/B Power Brakes
T.P.I. Tuned Port Injection
DIA Diameter
P/S Power Steering

Emissions Code Key

The application guide above specifies which Emissions Code applies to this part. Doug's Headers uses a voluntary product identification program whereby all mission-sensitive products can be identified by placing numbered labels in product packaging and listing corresponding numeric codes next to each part number. The corresponding numbers and explanations are as follows:

This Product has been granted a California Air Resources Board (CARB) "E.O" (Executive Order) Exemption, or is considered a Direct Replacement or Consolidated Replacement part. It is 50 State Legal when installed on the appropriate vehicle per the Manufacturer Application guide and Installation Instructions

This product is Legal for use on 1974 and older non catalyst equipped vehicles and is considered a "replacement part" per California Air Resources Board regulations, as long as ALL emissions sensitive components are retained, including A.I.R., EGR, Heat Risers etc. Failure to retain any of these components, or use on any 1975 or newer catalytic converter equipped car would render this product Illegal for Street or Off Highway Use in California, or in states that have adopted California Emissions regulations and may only be used for Closed Course Competition.

This product is Not legal for Street or Off Highway use in California or in states that have adopted California Emissions Regulations and is only intended for Closed Course Competition use, except 1965 and Older US manufactured California Certified vehicles, 1967 or older US manufactured Federally Certified vehicles, or 1967 and older Foreign manufactured vehicles which may have any aftermarket add-on or modified part installed as long as the vehicle can still meet the tailpipe emission standards for the year of the vehicle and retain any original or retrofit crankcase control (PCV) devices and NOx device required for the year of the vehicle.

Additional Information

Doug's PASSENGER CAR HEADERS Long Tube Hi-Temp Black Coated Header development and design is complex and requires a substantial amount of time and resources to do the job right! Many manufacturers are unwilling to make the commitment and instead offer compromised headers at lower prices. Doug's will not compromise performance, quality or fit to compete with inferior designs at cheap prices. Every Doug's header is tuned with the proper tube size and length to efficiently remove all the exhaust from each cylinder, reducing pumping losses resulting in a dramatic increases in horsepower and torque. Doug's headers are carefully developed on the vehicles they are intended to fit and are re-checked numerous times during the design and manufacturing process.

Download instruction manual

Instruction Manual
Instruction Manual

Download PDF

Shipping & Delivery

Our ignition and exhaust products ship from our warehouse in Lenexa, KS. Our normal shipping time is 2-3 working days when the part is in stock. Freight is FOB, Lenexa and all claims for shortages, damages, etc. must be filed by consignee.

All packages must be inspected upon receipt for any missing or damaged goods and claims for such must be made within 7 days of receipt. PerTronix does not currently ship our products internationally from our web store.

For international orders call 909-599-5955 or connect with us here.

Returns & Replacements

Returns at Pertronix are accepted within 90 days of purchase with prior authorization, ensuring items are in new, resalable condition. To initiate a return, call for an RGA and follow provided instructions. Customers are responsible for return shipping, using a trackable method.

Refunds exclude initial shipping and handling fees and may be subject to a restocking fee. For defective or damaged items, contact Pertronix directly. We are not responsible for user-initiated damage/loss of parts.

For complete details, visit our Returns page.

Reviews

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