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Blow Performance Exhausts Specifications

Important information for rubber mounted engines with excessive vibration:

Fit a support bracket from the gearbox to the center bolt housing with all engines that vibrate excessively to prevent damage. Highly recommended for Dyna models, high torque & race engines.

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Click here for installation instructions


  • 2500 RPM - 108 (guide only)
  • Equipment used - Compact Digital Sound Level Meter QM1589.
  • Engine tested - Harley Davidson 103 CUBIC INCH
  • (Readings may vary from engine type and size. Please check with local authorities for permitted levels)


  • Blow Performance Exhausts are a 3-Stepped Tuned Header system, the product achieves greatest performance with a sports/performance air filter and without baffles. This system is designed for race and closed circuit environments.
  • Compatible with most Stock Harley Davidson Sports & Touring Models & Left hand drive Chopper, Bobber and Customs with 80 ci - 131 ci Evolution & Twin Cam Engine.
  • Will fit some right-hand drive Choppers and Customs depending on the gearbox clutch cover clearance. A support bracket may be needed. With all custom's some modification may be needed.
  • Will not fit models with large center foot boards, replace with smaller footboards or forward controls.
  • Dyna Models need replacement of the large oil filler cap with a small oil filler cap. Accessibility to the oil cap is difficult when servicing however, undo the rear exhaust pipe for easier access (5 Minutes). With all rubber mounted engines with excessive vibration place a Support Bracket from the center exhaust connection bolt to the gearbox or engine to prevent damage to the exhausts system.
  • Breakout models need slight trimming or folding on the back-exhaust heat shield to prevent the exhaust shield touching the oil tank This may be required with other models with large oil tanks.
  • Comes with 12 mm & 18 mm compatible 02 sensor adapters and blanking plugs. Suitable for carburetor & EFI models.
  • WILL NOT FIT Harley Davidson Street, Sportster, V-Rod & Milwaukee-Eight Harley Davidson models.
  • Engines that vibrate excessively (EVO pre-2000, rubber mounted engines, Dyna, Touring, High Performance & Race) place a support bracket from the center exhaust connection bolt to the gearbox or engine to prevent damage to the exhausts system.
  • Warranty and Terms & Conditions can be found at the bottom of this page.


Downdload the chart: PDF   Excel compatibility chart



Support Bracket Suggestion modification parts
Centre Controls modification parts

Suggested Air Cleaner Styles

air cleaner styles
air cleaner styles
air cleaner styles

Suggested Dyna Oil Cap Styles

dyna oil cap style
dyna oil cap style
dyna oil cap style
Trim or Fold Rear Shield rear shield
Shield Spacing shield spacing
Washer Spacing washer spacing



chrome heat shield combination



matte black heat shield combination


  • Use gloves and assemble on nonabrasive area, use cloth towels or similar.
  • Take extreme care when working with the ceramic matte black coated products.
  • Assemble flange, retaining ring and gasket onto exhaust manifolds. Use existing or replace with the larger Flange Gasket set.
  • Leave an even gap along the exhausts pipe when changing heat shields.
  • Install rear exhaust pipe first then the forward exhaust pipe, keep in place loose by head stud nuts then join with the center exhaust connection bolt.
  • Pull the exhaust away from the gearbox clutch cover (3 mm 1/8'' to 5 mm 1/4"), make sure the exhaust system is in position then tighten all nuts and bolt evenly.
  • When fitting a support bracket from the center exhausts connection bolt to the gearbox or engine tighten the gearbox or engine side first.
  • Place 1 or 2 spring washers (5/16"- 8 mm) in-between the center exhaust connection bolt for added spacing.
  • Tighten bolts after first start & then again after first run. Check occasionally thereafter.
  • Install a sports performance air cleaner & tune engine (REQUIRED)
  • 1.5 mm solid Copper shields are coated with Everbrite Coating Protecta Clear®. May need recoating from time to time to prevent tarnishing.


  • 2 x Chrome or Matte Black Exhaust Pipes with 18mm O2 Sensor Compatibility
  • 2 x 12mm O2 Reducers
  • 2 x 18mm Blanking Caps (For Carburettor Models)
  • 2 x 1.2 mm Solid Rose Gold Polished Copper Heat Shields
  • 2 x 5 Layered Showroom Finish Chrome Heat Shields
  • 2 x Ceramic High Temperature Matte Black Heat Shields
  • 2 x Removable Quick Release Baffles (Pre-Installed)
  • 1 x Centre Fitment Bolt
  • 5 x Stainless Steel High Tension Clamps
  • Does not include Flanges, Retaining Rings, Gaskets and Nuts. Purchase new or use your existing.


Our product is warranted against defects in material and/or workmanship for a period of 24-months from date of purchase. Painted, chromed or plated surfaces are not warranted against discolouration or rust. We recommend using Everbrite Coating "Protecta Clear®” or similar product to maintain Copper Shields. Labour costs and return freight are not included in the warranty. Incorrect installation, or modified systems will void all warranty.

Authorised warranty can only be issued directly from Blow Performance Exhausts Pty Ltd. All returns and warranties must be accompanied by a return authorisation number from Blow Performance Exhausts Pty Ltd. Proof of purchase must be provided for all returns or warranty claims.

Manufactured in China.


Emissions Notice to Customers in California and other States that have adopted similar laws

Compatible with most Stock Harley-Davidson Sports & Touring Models, Customs & Choppers with 80ci to 131ci Evo and Twin Cam Engines.

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