i got a 84 gsl-se with a fuel injection rotary. i have to replace the exhaust from the header back to muffler. since the cat converter for this car cost $2100 brand new do i have to replace it? my main concern with not having one on there is will it mess up the compression if i just put a different system with no cat?

 

If you have smog testing you need a cat. If not, dont worry about it and have some nice custom stuff made. I think most people run 2.5 inch piping.

 

yeah i live in michigan so theres no smog test but im just worried about compression ive head the rotary's need certain compression

 

Open the exhaust up on that thing. Header all the way back to a muffler. You will be "very" happy with the power increase... I was.

 

6-port 13B engine? I'm wondering when you talk about compression, do you mean exhaust pressure instead to open the 5-6 ports? I believe with a low restriction exhaust they will still open, but maybe at higher RPM's. Racing Beat makes a convertor replacement pipe with the 6 port actuator flange fitting.