Joekaistoe

Background: I have a 1981 12a stock port with an RB header, RB presilencer, and a 79 intermediate pipe and stock muffler.

Is there any performance gain to be realized from swapping to a 1981-83 or 84-85 intermediate pipe and muffler?

​​​​​Intuitively, it seems like there would be, since the 81-83 system splits to 2 pipes, and the 84-85 has a larger diameter pipe, but that doesn't mean there is in practice.

I'm not looking for a louder exhaust and sadly recent reports of RB mufflers are that they are significantly louder than older ones, hence the question on stock mufflers.

chirmstream

I just recently installed a complete racing beat street port exhaust system with the long primaries on my s2 (ordered around July 2022) and I have to say it’s not much louder than stock.

And by not much louder, I would group them in the same loudness class if you will.

Richard Miller

What ever missteps RB may have taken, I believe they corrected course. Kids GSLSE has the RB muffler and has sporty sound. Definitely not loud. Tad louder than modern cars. Not by much though.

My ‘80 has a 3” exhaust. Muffler, pre silencer, also running a GESI catalytic and a turbo. That car is louder than the SE, but not by much.

Joekaistoe

I appreciate the update on the racing beat mufflers, but I'm also not looking to spend $2000 CAD on a street port exhaust system at the moment. If I can get moderate gains for cheap from cutting the exhaust off of an 82 or 84 in the junk yard and still not wake the neighbours, that would be ideal.

Does anyone have experience experimenting with the stock exhaust systems?

Toruki

I have the stock exhaust with a Bonez free flow cat on my 83 GSL. It has a reasonable sound and bolts right in on my system. I also had installed their race pipe instead of the cat and that had a really nice throaty sound, def louder than stock but not obnoxious. The smell with the pipe was pretty strong and my wife did not appreciate it so that's why I went with their free flow cat as a compromise. I like the setup.

Here's a link to their stuff: https://rx7.com/store/rx7/saexhaust.html

And here's a thread from the forum: https://www.rx7club.com/1st-generati...4-gsl-1150997/

Holdfast

There is a small increase in power with the duel outlet mid pipe and muffler from the 81-82. Exhaust tone and sound is improve also. Ive always had 84-85 my dad had a 81. His car had a worn out motor but was faster. I got a twin pipe from the junkyard for my 84.. Noticed the difference right away.

LoneStar23

Anyone know what is the power gain from the Bonez free flow cat? Looking to replace the original cat on my '85 12A with something that is less restrictive.

And does the air pump get disconnected or removed altogether?

Thanks.

LoneStar23

Based on what I have read, best to reconnect the air pump: (a) its draw on the engine is minimal (b) will help cool new cat (c) won't upset anything else. My engine is bone stock, rats nest has not been removed. Car is running nicely in current state; however, the old cat smells foul and my guess it is at least partially blocked.

A place nearby installs MagnaFlow product. The tech there has had multiple rotaries and recommends I go with a Magnaflow cat. Not sure which model. My plan is to sell the old cat to local recycler.

Frogman

Call Ari, he doesn't have stock and a lot of that stuff. I know you are looking at THAT website because that's the only place that bonez set up still exists ( sans looking them up part number-wise) .
Also, you have to run an air pump or your cat doesn't do its job as well as it could.