I have a stock 86 fc and i was wondering what kind of exhaust i should get. I want like a low deep roar. I'm thinking of doing a 13bt motor swap one day, would i have to buy a whole new exhaust or could i keep the one i bought and just change the headers?

 

Chances are, if you buy a good high-performance exhaust, you'll be able to use all of the components except the headers in a turbo car... downpipes aren't that expensive anyway.
Basically any exhaust you get with a rotary (at least a 2 rotor) is going to sound like a lawn mower, it's inevitable... but if you don't want it to be obnoxious, and rather more mellow and deep, go for dual exhaust.

Lots of guys here will recommend the Racing Beat system. The catback for it is like 550 bucks if I remember right. Greddy Power Extreme catback (very expensive (>700) , very hard to find) or the Rotary Performance 50mm catback (relatively cheap (400'ish?) , www.rx7.com) would suit you well too.

Just look around.. but I'd make sure to stick with a dual catback if you want a lower, deeper tone. If you're looking for a screamer, get a single-exit.

edit:
http://www.racingbeat.com/resultset....rtNumber=16420 there is Racing Beat's catback. Go to racingbeat.com, click on the Rotary link, and search through the Exhaust components to find more stuff (headers, presilencers, etc)

 

DOn't bother buying the exhaust until the swap starts IMHO. You'll eventually want a larger diameter and opinions would probably change on what you want, its purpose, and so forth.

 

http://videos.streetfire.net/search/...41CB4EBC9B.htm
imo the RB set up is awesome