I don’t plan on running 400hp on the CA, so should I bother with 3" catback?
I’m going to have a 3" DP to a 3" cat.
And then I figure 2.5" from the cat to a 2.5" muffler.
Should I go all the way to a 3" or is there no real point?
3" exaust be better regardless of the amount of hp you are planning on running.
Agreed…
N/A or Turbo it will give you better responce and better numbers.
Thing is though if you are looking for something quiet and
streetable go with a 2.5" Mike on this board has a CA with a
2.5" exhaust and his car is quick as a whip and is quiet as one too.
ive got 3 inch with a silencer and its relatively tame
With a Silencer it’s not a true 3" then.
It acts as like a 1.5"
I would go 3" but it is up to you, with 2.5" you will be losing some power, but if you decide to go that route, I will have a 2.5" inlet dtm muffler for sale in about a month.
yah but at least i have the option to whip it off whenever i want. for daily commuting i’ll have it on but when i have the urge… i jst unscrew the thing and let it rip
Looks like i might as well go with the 2.5" for now, if I get the urge I just have to replace the cat-back anyway. I’d rather not draw a lot of attention 
Well good luck not drawing a lot of attention with a right hand drive car.
That’s not the kind of attention i’m trying to avoid
stop being a baby.
the difference between a 2.5 and 3" catback on a turbo car is minimal, get a apexi exhaust and it will be uber quiet because of the massive resonator, and youll get better hp.
Adam , N/A cars wit 3" exhausts dont always get better numbers because they need some backpressure or else you get shit torque.
almost all mustangs run 2.5 max.
Yeah Dual 2.5"
I gained 15hp with my GP sports Exhust…
2.5" would be ideal for me on an n/a ka. Turbo car gains would be better with 3" exaust.
if you’ve got turbo dreams, might as well do it right the first time and go 3
I’ve been told that 2.5 is better if you are going to stay NA while 3 would be choice for forced induction… i’m no mechanic tho
With forced induction bigger is better. You can run with out an exhaust at all to make the best power for forced induction. Why you ask? Because you don’t need any back pressure. All your back pressure is at the manifold to turbo inlet. For a N/A car you want about 3psi (i think its psi) of back pressure so that you can have your low end power. If you were to open it up you would have bad low end power but still good high end.
didnt spell cheak this.