hello all,

i was wondering if i should expect boost creep with a 4in cat back exhaust..... the exhaust is the apexi GT spec. i know there is boost creep problems with full exhaust but i'm just doing cat back for now or poss. a DP as well but no high flow cat.

while i'm on this note, am i correct in assuming that the 4in exhaust will help the stock twins spool faster? i'm sure any bigger than that and there isn't enough back pressure.

thanks for any help/suggestions.

 

If the stock cat is in place i would think not but i would expect fitiment issues going from stock to 4 inch stuff. i had a time finding gaskets to fit my Greddy SP cat back to stock in a pinch.

 

well i believe the end that meets the stock cat is 3inch and them opens to a strait 4 inch... i'll find out son enough i guess.

 

from what ive read in the past couple of years, you shouldnt worry about back pressure since your in a turbo'd car...NA on the other hand, then you run into some problems...i havent had a chance to install a 4incher on anybodys 7 so cant help, sorry.

 

guess that makes sense with a force induction motor vs. N/A when it comes to back pressure. i think i'll be in good shape.

 

I get bad boost creep with the apexi GT spec with a straight through resonator. I have a ported and polished out wastegate stock twins. It sometimes creeps to 13-14psi from 10psi on a cool night.