RKAutowerks

We're introducing our 321SS Tuned length stepped headers and light weight muffler combo. The system is designed and built by Charles Dundon. Many of you who have 996 GT3's and 997 GT3's know of Charles and his header designs. They make 40+ whp over stock, sound great and are well made in the USA by Charles.

The system is available in 2 configurations.

1. With Bypass Flaps
You retain your ability to open up the exhaust or quiet it down. It's still a bit louder than stock, but not annoyingly so based off of our 996/997 systems.

2. No Bypass Flaps
Straight through, no flaps as loud as you like!

Here's a walk around video of what the system looks like
https://vimeo.com/141632709

Here's video of it in SEAPAR's car at the Ridge here in Seattle
https://vimeo.com/141628454





991 GT3/RS Charles Dundon/RK Autowerks 321 SS headers.


991 GT3/RS Charles Dundon/RK Autowerks 321 SS Headers and Muffler



Weight of the system is lighter than stock by far. Stock is 86 lbs, and the system without flaps is 32lbs, and WITH flaps is 36lbs This is complete header flanges to the exhaust tips including ALL hardware, clamps, straps etc.

Our 991GT3 full exhaust made 30+whp on the dyno. We're working on a refinement to them, as we think there is 6-10whp more to get.

This is the current configuration.


You'll notice we chose to do a run at full throttle through the gears... (sounds glorious btw...)


The reason for this is the way the ECU adapts, it's a very active short term adaptation. Once we can tune the car's ECU we'll be able dial it in a bit better and also fix a torque dip we have in the lower rpms. This is also one of the reason we chose to illustrate the power gains of the system with a multi shift full power dyno. The car shifts at 6500 rpm and when on track, you will likely be keeping the revs above 6000 anyway.

You can see the torque dip below. We're working to drive it even a bit further down the rev's. We believe we can get the dip to be gone by 6000, this work is happening 11/3.
The torque reduction is due to excessive cam overlap in the factory ecu programming for emissions. This is causing the intake air to escape out of the exhaust valve (overlap is where both valves are open at the same time) This in turn causes the mixture to be a little rich in the cylinder reducing torque in this region. This only happens at full throttle as 0-70% throttle doesn't make the cams move to the same extreme as full throttle and you won't honestly notice this dip when driving the car. part throttle in 2nd gear rolling into 5k will still break the tires loose...





The flaps installed are phenomenal quality cast 347SS pieces and quiet the system down perfectly for cruising around town. I was in my friends 997.2RS and it was far louder with the stock exhaust on it than the 991GT3 was stopped at lights or cruising to the dyno today. No upset neighbors or spouses with the flapped setup! There is a slight drone 2200-2800 that we're working to reduce and believe in the latest revision we will.

The system is catless, and practically guaranteed to have no CEL, but without cats it is an "racetrack or offroad use only" product. We have been driving it around with the system installed and no CEL or cat efficiency issues at all.

We're looking to get 10 folks interested in the Group Buy at

With Flaps: $6500
Without Flaps: $5650

So Far we have 2 systems sold outside of Rennlist, SEAPAR is a potential third once he hears it with the valves installed.

991 GT3 Dundon/RK 321SS Exhaust

SamFromTX

Can you explain how does it not throw a CEL with no cats?

Ur20v

Looks great system Jamie/Charles... did you release the 997 version?

MileHigh911

Sure does sound more exotic when running next to that wall. Any Db readings?? Also, when/if you get the dyno graph, if there is a proven gain of HP, then I assume it will grab everyones attention.

Charles@dundonmotorsports

The DME is looking for a specific O2 sensor voltage to know the cats are working correctly. Once you fully understand the parameters of what the DME needs to see as well as many other potential issues for a code to be thrown other than p0420/0430 (like a sensor aging fault) then you can defeat the system. My O2 defowlers are well proven and being a permanent design and welded not threaded in does help make most of the difference.

Hopefully this week. Just finishing a few details as well as have been trying to get a 3.8 dyno to post up since the 997 is more engine specific.

-

Yes the exhaust does sound very unique. Once I get the flaps installed here soon I will install the system again and drive and get external sound from outside the car. Meaning me driving and someone else taking video.

As for dyno, I am confident the system is making power as it is built off of the same experience/math/science as everything else I build. Hardest part about dyno on a 991 is you have to use a PIWIS 2 tester to put the PSM control unit into the mode so you can dyno. Otherwise you have to do a linked 4wd dyno which will show probably a 100hp loss and not be accurate.

If anyone can get a legitimate baseline stock dyno of their car and they want to buy a system we might be able to make you a better deal in exchange for dyno info

Alan C.

Nice to see someone using 321 instead of 304.

Charles@dundonmotorsports

I refuse to use 304 on a GT3 exhaust as there is no longevity in the product, only initial profit for whoever makes and sells it. 321 has always driven the price of my exhaust systems up high, but atleast this way making them 10 at a time I can keep the cost low and return the savings to the purchaser. plus with 321 I can keep wall thickness down and retain strength as well.

my 20ga 321 996/997 center exit system weighs 24 lbs

Serge944

Have you experimented with merging the two exhaust banks - is that an option? I haven't heard your system, but from my past experience, the flat-6 sounds better with the exhaust banks merged (the signature 997/991 sound compared to the 996).

Also nice to see the use of quality stainless steel, that is designed to be used in high temperature application.

fxz

Any dyno?

Charles@dundonmotorsports

The 996 GT3 I build a dual exit setup with X pipe, which is my AVATAR pic. I build that setup dual or single and the dual exit with X pipe merge I think is a little louder than the single setup but it does make a little more midrange. Otherwise to me they sound the same.

I have messed with one 997 by merging and building a 6-2-1 header setup and exhaust but what made the most power and sounded the best was too exotic to fit under the bumper and be packaged, so it was just a learning experiment. Either way a good exhaust note starts with correct primary length.

No, I do not have a PIWIS 2 tester so I do not have the ability to dyno unless I buy one, or someone loans me one, or someone else does a 3rd party dyno test. I have one planned with the first customer that has prepaid for this setup, but that will be a few weeks as it is out of state and someone else will be dynoing stock then swapping exhaust, drive around and then redyno, he has access to a PIWIS 2 tester which is the key.

Jamie_GT3

PIWIS 2 located and secured. Should ship the end of this week, receipt middle next and if all goes as planned Dyno that weekend or Mon/Tuesday 26th/27th.

m42racer

Finally a proper set of pipes. Made from good quality steel and appear to be well designed.

Jamie_GT3

And a lifetime guarantee against cracks, splits or anything other than crushing them or regular muffler repacks!

4porsh

When I was looking around for a special custom exhaust that had all my boxes ticked I ended up get a Charles Dundon exhaust. I talked with two other RL folks that have his exhaust and wanted to know about their experience with Charles and how they liked the exhaust. Both have the highest respect for him. So I happened to be on a job up in Seattle and met Charles twice to talk about the exhaust. Even went to his house. This guy is the real deal, super pro that blends the science with the art to create outstanding product. He tried to tell me the science of his plans to build my exhaust but I brain was about to explode and my eyes glazed over. My friend and I both purchased his exhaust and love it.
Every time I'm at the track people come over to say it is the best sounding car there. Even on the free way people freak out.

Just ask Mooty, he has seen, heard, and run with me on track.



Joe
Santa Monica, CA

mooty

I've been called!

yes I spoke with Charles several times and he knows his stuff
no shortcuts

sounds good
welds are beautiful

go for it