dxb_911

Any recommendations on a center section for best sound with Dundon Race Headers and side muffler bypass?

I initially installed the Dundon Race Headers with a GMG Center Bypass on my 991 GT3, and I loooooved the sound. Amazing at WOT and on the track. It was suffering from too much of a loud drone when driving at highway speeds though, so I pulled off the GMG and put the stock center muffler on, but now I miss the loudness of the previous setup.

I am looking for something that will give me the best of both worlds. The amazing loudness of the GMG Center setup at WOT and with the valves open, but without the highway speed drone when the valves are closed.

I am considering the Dundon Black Center muffler or the Fabspeed Mini Maxflo Center. The Dundon is quite expensive compared to the Fabspeed, adds a little extra weight over OEM, and I am unsure if it will give me the desired effect as I haven't heard the setup in real life. I am even more unsure about the Dundon Headers/Fabspeed Center combo as I haven't been able to find any reference to anyone that has tried that setup. Fabspeed says it would be a good middle ground between the stock muffler and the GMG, but that's just their word. I assume it would be similar to a complete fabspeed setup with their race headers, but I haven't found a video with that either (at least where the setup is described properly so I know what I am listening to)

Any other options I am missing, or anyone that have experience with a setup that works for them? The Dundon headers are staying on. I am only looking for a center option.

Alan C.

I've heard the Dundon racer headers/black combo and I have a feeling it is what you are looking for. C2Spin had the combo on his 16 RS, amazing sound.

Soul Performance

I'm also going to say the Dundon Black Center Muffler would meet your goals the best with that header setup.

Regards,
John Gaydos

Seth Thomas

Yes it is addicting sound. Drove Dundon's new .2 GT3RS Lab Rat around Road Atlanta for a few laps during the SmokiesGT event and it was awesome sounding. I have a black muffler coming my way to go with my street muffler after that experience.

John@Fabspeed

Phil from Fabspeed here.
Glad you are loving the Dundon headers. We have run our race headers on the Mini Maxflos which is very close to the same set up. What center section are you running right now?

Alan C.

Really? 🤣🤣

John@Fabspeed

Here is our Race headers with some of our advantages. AS you can see they are very close to the same set-up.

GT3 KSA

dxb_911 i was running JCR center bypass with dundon race headers

I had no drone and it sounded great when in cabin with a lot of drama going on

Out of the car it was too loud but it might be what you are looking for. I also did a dyno test recently then removed the JCR center and put stock. Stock showed more power so i went ahead and ordered the black since it is same design as stock but is guaranteed not to crack.

A friend just picked up the JCR from me to test it on his stock RS. If he likes it he will buy it but if he does not then i can sell it to you.

Here is the video on the dyno with the JCR / dundon combo


you can't tell but it is so much louder than the stock / dundon combo that everyone at the shop had to cover their ears when it was in high RPMs

Here is the link to the dyno thread

https://rennlist.com/forums/showthre...1144960&page=1

PS i think we are both in the GT group i was going to post my JCR for sale but like i said my friend is testing it out on his stock RS let me know if you are interested in case he does not end up buying it

Dougr743

Seems center muffler deletes make less power, than the stock. Is this only when you have side deletes and add a full center delete. or is this due to back pressure? What is the reason?

Alan C.

Looks a lot better than your old stuff and nice to see you did a 180 on your position on 321 SS. Competition does improve the breed.

dxb_911

Do you have a link to any videos with that setup?

Yeah, I think you sent me a video in the group once.. This is the JCR silenced center right? It may be an option, but probably the Dundon Black is the better choice.. I do feel a significant power difference (or at least improved speeder response) with the stock muffler compared to when I was running the GMG bypass, so a center bypass is probably not the best way to go.

I definitely feel improved speeder response after putting the stock muffler back on, so something is lost with the center bypass. I'm also wondering what the reason is though.

JCR-Porsche

Dyno tests need to be completed back to back, same day, in order to hold any weight. The test referred to above was not completed on the same day, far too many variables. Even strapping the car down differently can cause huge discrepancies in test results.

In our testing our centre delete gains 5-7hp, no loss of torque. This is on a hub dyno, back to back 100% repeatable results.

We don't push the gains for the centre delete because in our opinion the centre and sides should be considered for sound improvements and weight savings, if you're looking for power then really you need to address the exhaust manifolds.

JC

dxb_911

Does that hold true with race Headers and side delete as well, or only with the stock exhaust?

I can certainly feel a difference now I put the stock center back on compared to the GMG center. (On my .1 GT3 with Dundon Race Headers) The speeder response is much better with the stock muffler. I haven’t dynoed the car, so I wouldn’t know about HP gains/loss.

I didn’t feel this difference when I had the stock setup and installed the GMG initially.

JCR-Porsche

I can't really speak for others but in our experience and in our own testing the results from our centres are consistent regardless of the sides and manifolds within +/-5% of delta. GMG does have a large expansion, this is something to consider especially when combined with large diameter headers with long primaries and no cats.

Direct replacement sides really make no power difference at all, they should be considered a weight loss and heat reduction measure (or sound amplifier depending on your set up)

Manifolds are where all the gains are at, thats why we made our manifolds direct replacement for OEM to give customers the best possible selection / choice of possible set ups. We're really not precious how our exhausts are used and with what other parts they're combined with. Another reason why we retain the OEM tip flange on all of our products too.

JC

GT3 KSA

The tests on my car were done all on the same day