hi folks, im after some advice as to what to further do to my car to achieve my goal of about 340 bhp and similar torque on an STi 8(blobeye)

i currently have:

(as it's an STi)

STi top mount intercooler
vf35 turbo
Sti injectores etc

and i have added so far(no map as yet)

3 inch centre section
afterburner vortex back box
simota panel filter

the main questions i have are about my exhaust set up.

the 3inch centre section narrows to join the 2.5 inch oem downpipe. do i need to get a 3 inch bellmouth downpipe to get decent results?or would a 2.5 inch decat d/p be ok?ive decided after much deliberation on decatted d/p so no suggestions for sports cat please lol.
(also..cant afford a new full 3 inch system... the bits need to be added to what ive got lol)

and would stainless headers and up pipe improve spool up and low down drivability?

any other suggestions?

and all these parts wil be fitted prior to a remap...so just wonderin what wil work best with a map.

thanks.

Tom

 

even though i said i wouldnt fit a sportscat...would a sportscat downpipe off a ppp sti give as good flow as a 3 inch decat?

 

ok here`s ya answer,

you have made a good start with the vortex back box and centre section and it will probably sound fantastic, but probably made only slight gains in power.

changing the downpipe will give massive gains in power, especially used with your aftermarket exhaust, i agree don`t bother with a sports cat, just get a open bell mouth 3 inch decat, don`t get a stupid twin dump down pipe there ****.
to save money keep your eyes pealed on ebay for a second hand 3 inch downpipe thats been heat wrapped, this will give quicker spool up as its holding the heat in the exhaust, i bought mine on ther for 130 squid.

now this will now give you around the 310bhp mark, plus loud bangs and flames from the exhaust.

ok, now the next step is a boost controller, and a boost gauge as the extra flow of the downpipe may slightly raise your standard boost making the engine overboost and hit fuel cut, but this probably won`t happen in the summer months this time of year as the outside temperature is too warm, but in a cold winter this may be a problem so do this next.

to get to ya 340bhp mark you need to looking to buy a walbro 255 fuel pump bigger injectors and a increase in boost when ya get ya remap.

take ya time and do everything step by step using and soucing as many second hand parts as you can, this way you will save a fortune.

hope this has helped.

Big Jim

 

IMHO !

You don't need to change anything, just get it mapped.
3" only necessary on the way to 400+ bhp.

Mine made 340 bhp with a full sports-catted TSL system, 2.5"/3" combo.

For top end power tubular headers will help give more power, ported standard headers will give improved spool..... you choose.

HTH

DunxC

P.S. Advise fitting an up-rated fuel pump, just to be safe !

 

Sports cats (the good ones) can flow well but are pricey. No cat means a possible Fixed Penatly Fine and 3 points on your licence, if you are pulled over for a random roadside emissions test. IMO not worth the risk.

If you just want improved WOT performance and big numbers, forego all this tuning malarky and slap a nitrous kit on there. It's proven technology and could probably give you an additional 75-100hp at a flick of a switch. I can post a link if you're interested.