To quote Racing Beat: "The bolt-on exhaust system increases horsepower approximately 32% - a 59 HP increase on a 1987 Turbo II RX-7!"
I believe it, too. I have seen dynos that yielded similar gains once an FCD was installed. The stock exhaust is very restictive and keeps the turbo from spooling very much. Once you open up the exhaust the turbo spools much better and creates significantly more boost, yielding more power.

 

custom 3" to a 2 and half inch Y with 5" tailpipes - no CAT who needs that.

 

HAH sticky it then

 

If we're posting pics, here are several pics of the GT spec exhaust--to compliment the ones previously posted by 'BoostinmyS5'.

 

Exhaust : Racing Beat Road Race (True Duals) Full System
Pros: 28% RWHP, and it sounds OMFGODLY at WOT
Cons : Heavy, and thats about it for cons
Some people say the true duals are no better then collected, but for a street car, they are incredibly wrong. This system sounds, in one word, outrageous.

 

Exhaust: Thunderfab DP/MP combo with TeamFC3S Carbon TI cat-back
Pros: Lightweight, sound was very smooth. Nice tone
Cons: Big tip exhaust, kinda drones at partial throttle/cruising
I loved this exhaust setup, but throught the different mods i eventually cut it all up to make room for different parts.
9.3/10

Exhaust: Racingbeat 2.5inch dp and midpipe with TeamFC3S Carbon TI cat-back
Pros: stainless steel racingbeat quality. Decently quiet.
Cons: not big enough, tone was not as nice as the thunderfab unit
Circumstances landed me this dp/mp combo for cheap so i used it. Meh, it works
7/10

 

Apex-i N1 catback. thunder fab DP MP. nice sounds.. lots of increased HP

 

this wont be a sticky... its nice to read through these ... but it doesnt answer the question about what works for each person. no engine specs are listed or even mods. But it doesnt matter still a good thread. hmm my setup:

Car - S4 n/a engine, mild streetport, just using the carpet skin w/ no sound deaden, rear tar removed only
Exhaust - RB header/collector, RB presilencer/cat, Stock S4 n/a y pipe and mufflers
Info - Gives a nice growl at idle and as you climb rpm it still sounds stockish but just slighty louder. There is a power gain but not as much as a full exhaust might have.
Rating - I give it a 7.5/10 ... why? cause its very nice to listen to, no drone/buzzy sounds, fairly cheap, and you wont get the cops attention. I would have rated it higher if there was a better power gain.

 

Exhaust Type: HKS 3" DP to gutted cat to HKS Hiper cat back (3" pipe, single exit)
Pros: Unique, noticable power gain, has held up extemely well through 5 hard winters, lightweight as well
Cons: LOUD. I thought it was cool when I bought it, but I think I am growing out of it. It sounds really nice IMHO, its just LOUD.
Rating: 7/10
Summary: If you are looking for something along the lines of an N1, give HKS a look. They don't disappoint with a well made, effective and good looking system. If you want quiet, go elsewhere.

 

60 HP mainly from the rise in boost that would occur with a upgraded exhaust. The car would make more power (since the point of it is to remove restriction) and more boost since the turbo can breathe. You'll boost from (example) 7 PSI to 11 PSI. I also say this thinking that someone is replacing an old, shitty, glogged out, and stock exhaust. How many people are replacing a good stock exhaust quickly? I do admit, 60 is a prayer if the car originally had a good functioning exhaust. Not with what 90% have.

I never made a downpipe reference. I meant a full exhaust on a turbo rotary. You made the downpipe reference. But I bet the gains from a downpipe alone would be pretty large.

 

I don't think you know how exhaust can help even an NA rotary engine. Kahren's stock system helped net him a large gain on his 180HP stock port NA.

Not like it matters, but Racing Beat's full exhaust on an NA would net 20+ HP (I don't 100% agree, but I don't think its impossible.

**** a header is 11HP on a ported engine (check the dyno section under 190HP Kahren dyno).

We're not dealing with d-series motors. We're dealing with rotaries who DO react with proper exhausts.

 

This is the **** that I was talking about. Go DYNO it and see if it made 28% RWHP instead of just posting what Racing Beat listed (ironic since I used them for a reference, but I am NO WAY CLAIMING IT). Thats just a blatent lie in my opinion.

 

Exhaust: RActive based custom exhaust (2.5" from manifolds through 3" X pipe back to dual 2.5" to the mufflers). !Cats or resonation.
Pros: Car sounds like a Corvette at pretty much any throttle position.
Cons: No major cons, the polished stainless tips/cans require a lot of polishing to keep them shiny. Need to get some ZAP goo to keep the shine on them.
Summary: Definitely one of the hardest to install systems if you consider the ENTIRE setup.

Just havin' a little fun.

 

Prove it

No independent dynos have ever been done, let alone accurately, to my knowledge. The only "dyno numbers" available are what Mazdatrix says when they used to make it. Never believe a company's dyno numbers. Next you'll be telling me that AEM CAI's really do give stock honda's 15-20rwhp.

That's just a bunch of opinion unfortunately, no validity in it other than your personal agenda. Sure sound is variable, I'll give you that, but the "best streetable exhaust" is not true duals.

It seems the basis for your opinion is purely on the sound. Performance-wise, true duals are bad, especially on stock port. With the correct porting it may work better than a collected system, but another setup could out perform still.

Look into the physics about it, a very long and tuned collector should be best, looking purely at the numbers. Take a look into 88IntegraLS's s/c thread and you'll see an example of what I'm talking about.

 

Back on task, noobs seem not to look for this thread, please rate it a 5/5 so we can get it sticky sticky sticky.

 

I said for a street car :P What I meant by my post was that for a daily driver / don't really care about HP these are freakin' awesome. Sorry, don't mean to post misinformation about HP, but theres also no one disproving Mazdatrix :P

 

This thread is stupid, full of misinformation, and nothing but butt dynos.

You should of let it die when it did.

 

Show me proof of one car with true duals running better then a 15.3 or making more then 160HP (Rarest RX) on stock ports.

 

All stock but with empty cats. It actually sounds good.

 

Exhaust: 3 inch corksports downpipe, soon custom apex gt spec cat back
Pros: both very high quality. nicest, deepest sound ever with the catback....would never change it for anything else
Cons: the pre silencer on the cat back is at least 2 inches below everything else on the car....so itll hit everything.
Summary: awesome combo. however, i dont like the silencer sticking down below everything else so im going to cut the pipe after the silencer, get some 3 inch ss piping and weld it so the silencer goes where the cat is because there is room to move it higher there, then weld a 3 inch flange on which will bolt up to the downpipe.

 

Oh man, I've had so many different exhaust systems it's not even funny. Here goes for all of them:


Exhaust Type: Stock N/A catback w/ downpipe and cat replacement pipe
Pros: Well, it's louder and taking out the cats is a good way to increase power
Cons: Sounds tinny as hell, the catback is 18 years old, so expecting it to sound good is ludicrous.
Rating: 4/10

Exhaust Type: RB Streetable Header/Precilencer, HKS Sport Catback
Pros: GREAT rotary sound, not excessive, stock looking with great power improvement on my N/A
Cons: Not many. Perhaps weight and flow potential. Good for stock/street port cars.
Rating: 9/10

Exhaust Type: Mazdatrix True Dual Exhaust System
Pros: PSYCHOTIC sound. Totally unique sound, mix of a ducati 748 and a chainsaw. They flow like mad. Not too loud, completely streetable, not a cop-magnet. Great quality, great sound. Very, VERY deep.
Cons: They flow like mad. Not recommended for stock port cars, at least have a street/bridge port, otherwise you won't gain THAT much power and your powerband will suffer.
Rating: 9.5/10


Turbo Exhausts


Exhaust Type: Full 3" downpipe/midpipe, smashing into a 2.5" RB catback
Pros: Sounds okay...sort of
Cons: Actually, it sounds kinda crappy. High-pitched, EXCESSIVELY loud. Sounds like an exhaust leak, mixed with a rattling flange. Probably flowed like crap.
Rating:3/10

Exhaust Type:3" downpipe, midpipe resonated with Dynomax Bullet, Y-piped into 2.5" dual pipes and old school RB mufflers.
Pros: Good sound, perfect volume. Not a huge attention-getter when driving around, but very nice, and very head-turning at full throttle. Good, fairly high-pitched sound at full throttle, sounds nice and racey.
Cons: Not many cons, good flow, good (stock) looks, RB mufflers are always money. I prefer the volume of this system, but I prefer the tone of the system on my FB.
Rating: 9/10

Exhaust Type: (this is on my FB that has a TII engine) 3" downpipe, 24" long resonator and one 6" Magnaflow race muffler with a turndown.
Pros: My favorite sounding exhaust. Sounded good even when the engine went kablooey. Lightweight system, very loud under full throttle, everyone (even the domestic guys) like the sound.
Cons: LOUD. Like, cover your ears loud. Almost as loud as my friend's externally dumped wastegate (on a piston car, so not TOO loud). I'm putting in a larger rear muffler to correct this but retain the same sound.
Rating: 9/10

I've had more combinations, but they're not really worth listing. These are the ones I do recommend though.

 

Exhaust Type: Stock Manifold --> Bonez Cat/Silencer --> RB Catback
Pros: Great sound, awesome performance gain
Cons: RB Catback is heavy and willl last longer than the car
Rating: 10/10 its been a great setup!

 

Exhaust Type:
1) HKS Hi-Power Single driver's side exit race exhaust
2) Greddy Extreme power with dual exit
3) Borla Cat-back With dual Boomer tips
Pros:
1) HKS - Great Hp boost over stock, great sound (not too loud at all), bragging rights
2) Greddy - Draws attention to the car, nice air-flow and great performance
3) Borla - Great Price, Street-legal in *most* states, signature Borla sound and Borla's Million-Mile Warranty
Cons:
1) HKS - Expensive?, Also depending where you live, it may not be street-legal
2) Greddy - A bit pricy and slightly on the loud side (tho it's not quite as loud as a Nascar )
3) Borla - Somewhat restrictive when compared to race-spec exhaust, but far superior to stock
Summary: I've owned 4 different 2nd gen's (1 coupe(sold 3 years ago), 2 TII's, and 1 TurboVert). The coupe remained virtually stock while I had it, but as for the other cars:
One TII has a Greddy Extreme power dual exit (Exhaust #2, It came with the car when I bought it; It was a little on the loud side, but performed exceptionally). (I wrecked that one and now use it as a parts car)
The other TII I just aquired last month, so I haven't really had much time to drive it yet. It has an HKS Downpipe and mid-pipe mated to a Borla T-304 stainless steel cat-back system with Boomer mufflers. (Exhaust #3, It offers a decent boost in Hp as well as the most unique sound. Also, it puts out the least emissions, so it might be your best choice if your state is strict about that).
The TurboVert is easily my favorite with the Full Turbo-back HKS Hi-Power system (#1 Exhaust). It's by far the most free-flowing exhaust of the three (which allows for the greatest boost in horsepower) and the 75mm piping diam. gives it a nice throaty growl.
Rating:
1) HKS Hi-Power - 10/10
2) Greddy Extreme Power - 9/10
3) Borla - 9/10

 

Exhaust type: Street (quiet enough for street use anyways)

Racing Beat header (2 to 1 design, and almost to nice to put on the car)
Bonez Cat (high flow I guess)
Borla Catback (stainless is nice!)


Had to add a 4" spacer to make the cat connect to the rest of the y-pipe, but was simple enough. At idle it sounds great, and is great under 3K rpm, but around 4K rpm it resonates way too much for my taste, but makes a nice warning indicator of when I'm going 80mph on the freeway.

Overall fitment of the exhaust is great, but 4K rpm resonance and adding a spacer are the only cons.