991.1/991.2 GT3, GT3RS, 911R, Cup,



Laurent purchased a Dundon Lifetime 321SS Black Muffler to go with his Race Header System and Carbon Dual Cone Intake "At idle, sound is suggestive: not that loud but you feel the engine can tell what he thinks. At low revs and duty, sound is soft. It is even strange how they managed to keep the car that streetable. When you push it... read more

Laurent, Reunion Island

991.1/991.2 GT3, RS and 911R Long Tube Street Header Exhaust System

991.1 and 991.2 GT3 RS 200 Cell Cat Long Tube Headers


Click on a photo to enlarge.

* Muffler shown is not included with the system, only to see how the systme goes together!

Dundon Convertible Street (Catted) tuned length headers and valved side delete exhaust system for the 991GT3 991 GT3RS and 911R are available now!  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


The Dundon Street Headers on 991 GT3 make
434whp peak
30whp at 8215rpm
26lbft, 23whp gains at 4586rpm

The Dundon Street Headers on 991 GT3RS and 911R make
445whp Peak
32whp at 8400rpm
29lbft, 24whp gains at 4478rpm


The 991.1 GT3 and RS with the catted system shows it's emissions based camshaft tuning for about 5100-6000rpm area. This stock tuning flattens the power delivery for about 400rpms and then climbs quickly starting at 5400rpm. This is completely fixable with a tune, but understand that many will not want a tune.

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 


991 GT3 Dundon Street (Catted) 434whp peak

991 GT3 Dundon Street (Catted) System vs Stock

991 GT3 Dundon Street (Catted) 26lbft and 23whp at 4500rpm

991 GT3 Dundon Street (Catted) vs Stock, 26wtq and 23whp at 4500 RPM

991 GT3 Dundon Street (Catted) 30whp max gains

991 GT3 Dundon Street (Catted) 30whp max gains at 8215RPM

991 GT3RS Dundon Street (Catted) 445whp peak

991 GT3RS Dundon Street (Catted) 445whp

991 GT3RS Dundon Street (Catted) 29lbft and 24whp at 4478rpm

991 GT3RS Dundon Street (Catted) 29lbft and 24whp

991 GT3RS Dundon Street (Catted) 32whp max gains

991 GT3RS Street (Catted) 32whp max gains

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 Street

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

Dundon 991 GT3/RS showing length of primaries and routing required to fit the cat2

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...

Video from the dyno so you can see and hear the awesomeness! You also get a good shot of how the headers are routed with the wheel off!

Dundon Street Headers on 991 GT3 - YouTube





Decided for Dundon because of the reputation and performance results. The system fits well and sounds beautifull in combination with the OEM muffler. I got what I was looking for and my GT3 is now even more fun and exciting to drive. Very happy with the purchase and excellent customer service. Thanks Dundon.

Michael from West Linn, OR
I pondered different systems and decided on Dundon because of their solid reputation, proven performance results, first rate construction and beautiful sound coupled with the black muffler. If you are fortunate to reside in close proximity you cannot go wrong in having them install as they are experts with their own product. I have no regrets and have become a true believer in Dundon’s quality and customer service. Thank you fellas! See you again!

Chris from Gig Harbor, WA
Great customer service and communication. I love the product and recommend it to anyone and everyone! The car not only gained HP from the system, but it sounds amazing while doing that. Very streetable configuration, cruising without the drone, but when you nail the throttle it wakes right up! Highly recommended.

Chase from North Palm Beach, FL
Excellent quality and craftsmanship. I bought the catted system, it sounds wicked, no drone and fits perfect. Sounds incredible throughout the entire rpm range. I can't say enough positive things about this exhaust system. Hands down the best customer service as well. This is the 2nd kit I've bought and wouldn't consider any other at this point. Thanks guys!

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