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    Pre-Owned Header System for 991.1 and 991.2 GT3, GT3RS, 911R and GT3 Touring.    2.5" Outlets are for use with Stock Muffler and 3.0" Outlets are for use with Dundon Mufflers.  


We were able to keep all of the things that people love about our race headers:

  • less weight
  • more power,
  • great sound,
  • quiet when you want it to be
  • no drone
  • lifetime structural warranty
  • 100% 30day money back guarantee
    • if you try it and don't like it, send it back we'll give you your money back!
  • Convertible to no cats with the swappable test pipes for track days (available separately).

We use 321SS (a superior grade of Stainless steel to the cheaper 304SS) and use a metal core spiral wound 200CPSI catalytic converter.  All our products are mfg in the USA in our shop in Gig Harbor, WA.

By routing the primaries up and positioning the catalytic converter more vertical we were able to retain 99% of the primary length of the race system. This is how we are able to achieve 25whp gains on the 991.2 GT3, 30whp gains on the 991.1 GT3 and 32whp on the 991.1GT3RS.  This is the most power from a catted 991.2 GT3,  991.1 GT3 Exhaust, 991.1 GT3RS Exhaust or 911R Exhaust system.


The Dundon Street Headers on 991.2 GT3

477whp Peak 

20-25whp gains at 8200-8500 rpm

40lbft-46lbft gains at 3000-5000 rpm



You get everything you love about the Dundon Race Headers, 321 SS construction, industry leading power, lifetime structural warranty, and 100% money back guarantee, if you try it and don't like it, send it back we'll give you your money back!

To that end, see the dyno below!

991.2 GT3 Dundon Street (Catted) 477whp peak 


Some pics installed on the car, the street headers are only about 0.5" shorter than our race headers. To fit everything we had to go up into the wheel well where the side mufflers sit. Only way to get the length required for real power gains...


Dundon 991 GT3/RS showing length of primaries and routing required to fit the cat

As you can see to get the length we wanted we had to go up, anything that can bolt up to the stock location is leaving power on the table...