I've been looking into different exhaust systems for the TII for a while now, and had finally decided that I'd probably just go to a single muffler setup, because the added performance/cost/weight of a dual system just didn't really add up to me. But I came across the RB system a while back, and saw that they claim 30% peak HP gain or 57hp on an '87/'88. I'm pretty new to the rotary, but that just seemed ridiculous to me. That's even more than what you'd probably get on a V8 sports car. I've never read those claims from anyone else's exhaust either.

So what I'm wondering is if this is accurate? Does anyone have any or has anyone found any dyno sheets to back it up? Also is it typical from any full exhaust system w/ downpipe in place of the cat on a rotary?

Also, sorry if this has been answered many times before. I searched around, and didn't find it.

 

There is a dyno sheet floatig around somewhere that shows a 54hp increase on an s4 t2 in good running condition.

I can say that their products are very expensive, but also of excellent quality and sound, as well as flow. I like to tell people that it flows almost as well as any straight through exhaust, but is almost as quiet as a stock exhaust with one cat removed. Fit and finish and durability are excellent. BTW, did I mention I have this exhaust on my convertible? Check the other thread for pics. Even on my nonturbo it is nice and quiet (I adapted a 3" turbo back system to fit an NA by having a custom midpipe made to bolt to the RB presilencer).

 

Hmmm alright thanks. I thought it was kinda expensive as well, but it seems like $700+ is the going price for a dual cat-back system like one from rx7.com w/ Apexi N1s, so this didn't seem that bad w/ the downpipe and presilencer. I have a while to think about it.

Thanks for your input, btw.

 

When I had the system installed a couple years back, I visited a dyno and the numbers were very close to what they claimed. And yes, they are pretty quiet when cruising and not too loud when WOT.

 

Okay, is this typical for an exhaust system w/ downpipe on these cars? The Mazda design didn't seem that crap to me to show such a massive power increase, like say a GM.

 

bolting a full exhaust on a nonturbo usually results in 10-15% hp. Bolting a full exhaust on a turbo usually results in 25% or more, because not only are you freeing up the exhaust, but this automatically raises boost. IN the case of the t2, it almost doubles it from the stock 5.5-6psi to 12-14psi in combination with an intake filter.

 

Alright, thanks. I still might end up going with the RB, because I don't like the loud blah sound of a lot of other mufflers. There's a 10AE around here that has the RB exhaust, and seems real quiet from the outside.

 

It's not really an issue of the RB turbo back doing this, its just the rotary's natural reaction to a free flowing exhaust. Im sure if you use any free flowing turbo back exhaust it'll give you substantial gains.
But I do like RB products for their excellent quality/styling but found the cost of the RB too much to offset the weight/performance gains of a Corksport system.
Again, it just falls down to personal preference. The RB does give excellent gains and like you said, is fairly quiet and the close to stock weight keeps vibrations in the cabin to a minimum. But some wouldn't find that to be a compromise and want the most power output from the turbo back and choose single.

 

There's no such things as too small diameter when bolting up exhaust to a turbo. Antime you free up the exhaust such as removing cats and larger pipe, you will have increased boost and horepower but you must find a way to control the boost and boost creep when doing so. Buy a real boost gauge and monitor it. I have 3" running from downpipe on back and the Y pipe is 2 1/2 x 2 and I scrape over speed bumps. Some people have run 3 1/2".

 

My personal opinion is R.B. is the "****". Its a awesome exhaust system, if not the best you can possibly buy for the RX7. I had a single exhaust setup on a T-II, and it worked quite well it consisted of a ultra flow muffler with a 3" downpipe it flowed very well, but was loud as hell, and not to mention that all the "DAMN" Honda idiots were always trying to run me on the street becuse the 4" tip was a real attention getter. It got to a point that the noise from this single exhaust system was driving me crazy, so i installed another ultra flow in the middle to quite it down a bit, it helped somewhat but it still was to loud for my taste, and a real attention getter with the cops. On my first t2 I had the first R.B. exhaust system with the small tips, it almost looked 100% stock, and when I would get tried on the street by a mustang, or a honda the end result would always be the stang/honda about 7-8 car lengths behind me.
They would always pull up alongside me asking me is that a stock exhaust on your car ? Thats one of the reasons I love the R.B. system, because its a total sleeper, not to mention the fact that it is quite, but at the same time not extremley quite, it has a beautiful exhaust tone. In my honest opinion its the best exhaust system for the T-II in the market as far as quality is concerned (Its all 100% stainless steel will never rust), beautiful exhaust tone, and best of all its been tested and its specifaclly designed for the Rotary engine by R.B. I sold the old exhaust system to buy the new one that came out not to long ago, and man let me tell you something, the new one is "SWEET" its highly polished Stainless steel, with bigger exhaust tips compared to the old system, and if you look closely you will notice it has two rotors engraved, one on each exhaust system, with the Racing Beat engraved on the side of the exhaust tip. Simply said this exhaust system is the ****, but dont take my word for it go to the R.B. website, and check it out for yourself. Like the saying goes you get what you pay for, not to mention the R.B. system retains its value if you ever plan on reselling it.

 

The true duals I have use RB mufflers, silencers, and header so I know something about RB and they ARE "THE ****"

 

Doesnt RB use mild for the pipe and stainless for the mufflers? Ive seen quite a few ads for RB products saying "little rust" and what not. Or did they start making them full stainless steel in the past few months?

 

I know the cans are SS but I think the headers are mild steel. I have no idea about the pre-silencers but the always come back to a brilliant shine when i get under there and buff it up.

 

i've got the rb exhaust setup for an n/a and i am very impressed with the quality of their work. pricey, yes...but i can definately see where my money went.

john

 

I disagree about the quality of my downpipe I got from them. It looks like a 2 year old welded it with a 40$ arc welder.

 

The header is mild steel I can tell you that.

You guys know Stainless and Mild Steel have different coefficients when it comes to heat and expansion right?

You guys develop any leaks at exhaust flanges in your systems?

 

No exhaust leaks here.

 

I didn't think so.. Still as always - I was just curious.

 

From the downpipe, how big is the RB exhaust? And how much does it really weigh to be so heavy?

 

No... but I dont drive my car enough to know lol

 

i want one.

 

I have the full RB turbo exhaust on my car and its sweet...sounds nice....and doesnt weigh too much....especially compared to the stock....cant say much about the performance gains since its the only exhaust ive had on the car (did an engine swap from n/a to turbo) but i would defnitly recommend it for some of the reasons listed about....its got a nice stock look to it but really nice looking tips as well....and if your gonna buy it check out fc3s.org they have it on special for 725 right now i think, much better than the 900 sumthin straight from racing beat

 

I transferred the RB Non-Turbo catback onto my TII and then bought the RB downpipe and presilencer, THe N/A cat back is the same as the TII except that the mufflers use smaller diameter internal pipes, might limit horsies, but it does help with the boost creep!! Haven't dyno'ed the car but its a MAJOR difference than the stock setup it came with (bought it from a rich old lady who took it to the dealer to get EVERYTHING done to it for its entire life!)

THe complete tubo exhaust system from RB still uses some mild steel parts... my advice is to buy the downpipe/presilencer system and the catback system as two seperate units, little more expensive, but your getting a whole stainless system. Call RB before you order, the guy told me that they are using up the stock of mild steel parts and them will be selling the complete system as stainless, they may be doing that now.

And as for expense.... the COMPETE system that i bought from Racing Beat, all stainless steel, was less that the cost of the greddy catback i was lookin at!!

I haven not had any exhaust leaks, HOWEVER, when the car is cold... there is an annoying "tinging sound" from the front of the exhaust system that i thought was a leak, however, after smoke testing it (put a couple drops of ATF in the spark plug holes), and found no leaks, i've determined that it must be the noise made as the hot exhaust hits the cold stainless steel, 'cause my buddies third gen with a stainless exhaust does the same thing, and it goes away when the exhaust heats up.

also.. the RB system bolts EXACTLY to the stock locations with no mods needed... NICE!

Also, you can't beat the guys at RB for customer service and satisfaction.a

 

RB is the ****. I have their NA system on my vert, and I love it. I had a little problem with rusting (damn Northeast winters) on the little pipe that comes out of the muffler and connects to the y-pipe, so I called them. They sent me two brand new FULL stainless mufflers (even that little pipe is stainless now) no charge. They even paid for the shipping of the old mufflers back to them. Now thats service... I'm definitely going to buy the full TII exhaust from them when I do my conversion.