Allright guys, first post ever here. Heres my plan. I have a non turbo 87 gxl. I plan to put on a new header, 3'' DP, keep the cats, use a straight through 3'' pre silencer that splits where I can run 2.25''pipe out the back. Make sense? That, or, new header, 3'' DP, keep the cats/MP, run a 2.5'' Y pipe connected to 2.25'' pipe that runs to the two muffs. I think I should go with the second setup in order to retain backpressure however. Any Advice? Also, assuming I do put on either one of these, will I have to worry about too lean/rich fuel? Do I need an fcd?


Mods so far include:
HKS Super Mega FLow Intake
HKS Injector Pipe Kit
Magnecor 8.5 mm plugs
Underdrive pulley kit
Tokico shocks and struts/Eibach springs (.75 lower)
Eibach anti roll kit
cusco strut tower bar
hose techniques silicon hose kit

 

No need for a presilencer and the cats. Gotta be one or the other. And NA's do not need 3 inch piping. Use 2.5 for a single or 2-2.25 for a dual.

 

Definitly overkill!! You'll be loosing power over a system with smaller piping like what Samps said. 2.25"-2.5" pipe for single, or 2" for duel. If its a non ported motor, then a single 2.25 is pleanty. Read Q&A's on Mazda Trix's web page for exhaust systems.

 

uh..........yer dumb?

 

the dual N1 cat back actually reduced one guys dyno readings on here ..... uhm last summer(???) it was posted. He did say that it was a little more responsive and he didnt notice the the power drop. I think i am remembering it correctly. It was why I went with a single N1.

rx7_ragtop has a custom 3" in his Vert but he is also about to last bit of his t2 conversion on it so he will need the exhaust.

If you want to do a large exhaust like that because of future plans then thats cool if you have means to do it inexpensively now. If not what your talking is over kill.

 

decided to go 2.5 DP, new cat, straight through muffler that replaces the y pipe into 2 2.25 straight pipes.