Looking to replace my 2.5" system that Come on the car as it's to quiet for my liking,

Are theremany benifitsto upgrading to a 3" system ? And is it worth the money ? Looking at a full haywaard and Scott3" system including down pipe ,

 

what power are you running?

the 2.5" has been used on 450+ bhp cars with good results

I have always used 3" systems and only have 330bhp.

The 3" usually has a deeper tone, I have had lots of good comments about how good my car sounds

 

Unless your getting it remapped i'd stick to 2.5" bore. Although i fitted a 3" system to mine with sports cat, turbo kicked in alot smoother.

 

If your just replacing the OEM system for a full 3" because it's not loud enough why don't you consider first going for a cat back system with a louder back box like a Ninja 2 or Blitz Nur Spec R? These will be considerably louder than your factory system yet half the money of shelling out for a full 3" system.

 

I'm currently running around 270/280 at a guess , have 2.5" strait Through so no cats , well only in up pipe as that's sti standard at the mo, but planning bigger turbo , pinks and another remap .
I have considerd the blitz nurspec and was a choice between that and the hyward and Scott jap angled as live the look of those , just tHe fact the Hayward and Scott doaent noarrow like the blitz so is a true 3"

 

Plius hoping the 3" would produce a bit more power than the 2.5" , just unsure if worth the extra money to upgrade to a 3" lol

 

3" more lag, increased top end (so you might see a bhp increase to tell your mates in the pub about but you will lose overall acceleration, I know what I would choose)

2.5" better spool, standard top end

Ive used them all 2.5, 3, 2.75, and found a 2.5 the best especially on a twinscroll, a 3" on a TS was horrendous and made it spool like a poverty spec uk car

 

I'd stick to a good quality 2.5" system. Can't see the point in a 3" unless your going for 350 + bhp and even then its more to future proof than anything.

 

There isn't a cat in the sti uppipe bud.

 

Ment to say still, I'm a wrx

 

Very very generally

2.5" low down torque
3" better at higher Rpm.

IMHO running under 360bhp on a UK 7krpm better to 2.5"
Running over 330bhp on a JDM 8krpm use a 3"

Although as said if not much difference in cost of a 2.5"-3" the system then 3" does have some future proofing

Tony

 

I found that the power delivery seemed to last longer with the 3" where as will the 2.5 seem to come in a small burst. If that makes sense.

 

Orderd a full 3" Hayward n Scott today, so my current 2.5" system will be up for sale soon,