red7

I'm trying to gather as much info as I can before I get an exhaust for my 12A (84GSL). First what is the diameter of the factory pipe for an 84GSL, is it 2"? RB says it uses 2" diameter for their street system and 2.5" for the street port system but with long primaries. Mindtrain also uses 2.5", short primaries. RB claims about 20% power increase at 7k and Mindtrain claims about the same. However I hear that in an article by Sport Compact Car they use the RB with a cat and got only 7% increase. My engine is stock port and I don't want to loose too much low end torque; 2.5" seems to much for my engine but RB has that with the long primaries that should help the low end a bit. What is everybody's opinion on the 3 different exhaust: RB stock port(2"), RB street port (2.5" long primaries), or Mindtrain(2.5")? Also I am more interested in bang for the buck not all out horsepower, is not going to be a V8 killer after all.

BadAssRX-7

well i have the m.t. stage 5 setup. that means its the same lenght as the stock but larger diam.(2.5") i had it header to tail pipes. it was loud with the presialncers, much better with a highflow cat and dam near stock sounding with the stock cats in it. i have the whole thing minus the header up for sale. its in good shape the tips are in great shape, i replaced them less than a yearago. Id take 350 plus shipping for the setup.
David

red7

So did you gain power througt the whole rpm range or just at high rpms? How come you are selling it?

Acuspeed

I believe the claimed hp gain for the RB system is if you buy the entire system. From your desciption, it sounds like SCC only put on the header and left the rest of the exhaust stock. Most likely, that is why they realized a smaller hp gain.

SCC (from what I've heard/read at least) is kinda strange. They seem to be able to modify cars and get little to no hp gain (even lose hp in the case of the PGT they modified a few years back), while the actual owners of the cars are able to modify them and make considerable gains ... who knows...

BadAssRX-7

Red, i have the exh on my 81 gsl "the beast", i bought a 83 l.e. and my "plan" was to swap all the stuff. But after getting the car and driving her i cant its a limited edition and i dont want to start hacking on it. so i started to part her out. i sold the dellorto, rear seat, front and rear airdams. wing.... still up on ebay is a 2nd body kit (versatec) some 15" rims, leather seats, stock radio. I really love the tone of the m.t setup. its a deep tone like a v8 ish at idle and it getts better from there. M.T. still sells all the parts if you ever needed to replace 1 and you can get the header for about 200 new from them.

GT1

"Get a hold of a November 1997 Sport Compact Car magazine. In that one they have a 1983 RX-7 S that they put Racing Beat headers and cat-back on, plus they use a RandomTechnology high flow cat. It ended up having one of the lowest emissions of all cars (even for modern ULEV ones!!) and it picked up 7% power at the wheels."

stats taken from SCC VOLUME9, NO.11 ("approx" is me trying to read their poorly labeled dyno chart)
-RWHP was 95.2, after exh it became 101.9 @ approx 6300RPM
-RWTQ was approx 95 lb/ft, and became approx 100 lb/ft @ approx 4500RPM
-HC emmisions went from 1800ppm with stock exh, to 7ppm with the RandomTechnology cat and RB exh.
-all other emmisions were WAY below required values but weren't stated.

This was my responce to a legal exhaust question from about a month ago. But if you dont need a cat where you live, DONT USE ONE because that seems to be what is costing the system that SCC used the 13% more that RB claims. The system SCC used was the RB single pipe one with the cat in the place of the presilencer directly after the headers.