I have a 99 LS vtec and am planning on running a T4 setup. Basically what i want to know is what size downpipe and exhaust to run, and about how much H.P at the wheels is expected @ 9 PSI. Im going to have the intercooler and a hondata, 550 injectors, walbro 255, and obd1 of course. Any info would be appreciated! Also if anybody can tell me about what RPM this setup will start to spool at that would be great too!

 

go for a 3inch downpipe,
faster spool up.

and i'd think that setup with hondata could handle 10psi,

not sure how much whp u'd get,
i just know it'll be alot

 

what trim t4? is the motor built at all? t4 is going to have some lag on the street brother..