I think I'm coming to the realization that my full 3" exhaust with a Racing Beat dual-tip catback and Magnaflow resonator is becoming a significant restriction for me. I always thought this setup was fine even for my plans of going to 25-30 PSi once I get my methanol kit. But after tuning a few cars with full 3" exhausts on stock ports and stock twins with nothing more then an intake and intercooler I've been pretty surprised.

I now have an A-Spec 500R-SP turbo and think going to a full 3.5" exhaust would be a good choice. I've been considering going to a 3.5" full exhaust with a 3.5" (90mm) piping Trust Power Extreme Ti-R titanium muffler (Does our Greddy sell these here?) with another 3.5" Magnaflow resonator.

My current 3" RB setup gave me 415 rwhp @ 18 PSi on a Mustang dyno and gets full boost by 4200 RPM even though the dyno shows otherwise. Does anyone who understands these things more then me know what I might expect with a full 3.5" exhaust vs my 3" RB setup?

And does anyone know if anyone makes 3.5" titanium resonators?



thewird

 

Titanium resonators will be hard to find... but definitely check out Burns Stainless Ultra Lite Mufflers. I just bought 2 of their mufflers and they are top notch! I can't wait till I get my exhaust built.

 

Anyone have any thoughts on the exhaust itself? The resonator question was an afterthought. Thanks.

thewird

 

I can tell you I have a 3" turbo tuf old school catback from pettit and made 372 hp on a dyno jet @ 16-17 psi on stock twins and a good street port. I switched it out to the RB dual and it only made 354 while losing 1 psi of boost due to the restriction. It was quite a noticeable loss of power on the street. I would try a different catback before tearing up you whole exhaust. My set up as of right now is all 3" w/ a petit downpipe, rx7store resonated midpipe and the turbo tuf catback. Great sound as well. G

 

there is a HKS 4 inch racing ti exhaust in the for sale section...

 

Was those dyno pulls done on the same dyno? I just find it hard to believe that the RB dual made that big of a difference. I've made more HP on BNRs than any 3rd gen I've seen or heard of and it was done while using an RB dual. I've tuned a lot of FDs with that exhaust and just can't see a 20whp loss. Not saying you couldn't feel any difference in the two units, just find it hard to believe that it was only due to the dual RB.

-J

 

Once my car is back together, I will try removing the RB duals on the dyno and see what the difference is and will report back.

thewird

 

Yes it was. Same day..

 

I'd recommend it. I've never ran my 500R with anything but the full 4 inch exhaust, but I'm very happy with the spool characteristics and response of the setup. This is with a larger 67mm compressor wheel, and I attribute the streetability of my setup in good part to the unrestrictive exhaust. You can look into Magnaflow resonators, I have no knowledge when it comes to Ti however.

I've posted this before but I'm very happy with my Apex'i Active Tailpipe Silencer. Really cuts down on sound alot during normal driving but when you let 'er rip the car sounds tee-rific

 

Out of curiosity what 4" catback are you using? I was also looking into the Apexi ATS since I want to cut down on the noise to not be harrassed by cops. It works with any 115mm tip right?

My mechanic keeps insisting that 4" is overkill and 3.5" would be enough but in the end I have the last say of course.

thewird

 

You have to note that the exhaust was restricting psi levels. Which is what is causing the loss. Further tuning w/ the rb could have produced better results.

 

Rich where did you find the Apex'i Active Tailpipe Silencer?

 

How much horsepower did you make with BNR's? Those have to be some impressive numbers. I'm assuming north of 420rwhp since rich put down around 420rwhp or so. Chadwick had a customers car that put down around 440rwhp before as well.

 

The Apexi GT Spec, which is actually 3.75 inch IIRC. Noise levels are actually pretty tolerable with the ATS in (ie you can use your cell phone w/handsfree while driving).

For perfect fitment I wanted an Apexi exhaust, I'm not sure it'll fit any 115mm tip. As long as it's not rolled and you don't mind drilling a hole for the bolt you could probably make it fit.


On fleabay of all places.....I did have to wait a few months for it though.

 

Then you can't really compare them now can you?

-J

 

426 rwhp on 16psi with a creep to 17.3psi on a MUSTANG DYNO. This number was repeated 4 times (give or take + -1) during the dyno session. But the biggest difference between this car and riches (aka my honEE bunEE ) is that it's a stock ported engine!

I know Chadwick’s work, and I think of him to be pretty knowledgeable, buuut I find 440rwhp kind of hard to believe. Especially because that pwer was made with the twins being run sequentially. None the less it could be true and if it is more power to em

-J