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do i new a 3 inch dp

G

gpgt2002

New member
This is kind of a dumb question but I keep going back and forth. I have ported front and rear manifolds, hv3 insert, 180 t-stat and a few other things i can't remember. Do I need a 3 inch dp or am I fine with a 2.5 dp
 


^^ X2

In my reading here and many other resources N/A engines seem to in general like a bit of back pressure. Unfortunately it seems to be a magic un-documented value for literally each car. IMHO you seem to have already achieved a good setup, going to super low restriction setup many not net you any gains.

 
Unless your going to put a ported TB, rockers, or a cam...then just keep whatcha got...although the 3" will flow a bit more, but probably not enough for you to notice.
 


i bought a new zzp 2.5 cat dp and my buddy was tellin me i needed a 3 but i wasnt sure because its a gt but eventully ill get a 3
 
2.5" isn't BAD for an N/A car...someone will probably bring up backpressure needed blahblahblah...but 3" won't hurt it either...it'll just especially help with the flow when you get more valvetrain mods or other meaningful bolt-ons...like a blower :D
 


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