I was doing a lot of research online and doing a lot of searches. I want to upgrade a brand new STi. I had a 2004 STi, but then something bad happened to it and now it's not here. So now, I was doing a lot of research and waiting. I want to keep the turbo stock. So this is what I figured from reading, searching, and more reading, the best things to upgrade are:

Uppipe (Helix)
Downpipe (Helix w/ high flow Catalytic Converter) I live in CA
Intercooler (APS Top Mount) I still want it stealthy
Exhaust (JIC Magic Full Titanium)
Tubing (Full Samco replacement hoses)

I was reading that a BOV won't do anything as far as power gains and will actually take away horse power and make the car run rich. There's a lot of mixed feelings about putting in an intake. Someone said that Shiv from Vishnu tuning doesn't put one in because an STi was dynoed and there was no noticeable gains with an intake. Can someone else expand on this? Is there anything else on the list that would make the STi more power efficient? Oh yeah, what would a Walbro fuel pump do if the car already has large injectors? Please also, correct me if I'm wrong on any of the information. Thanks a lot.

 

No need for a up pipe, ours are catless and from what i have seen it will make almost no diff.
also I say get it tuned (Acessport or other) should also be near the top of that list.

 

suggest you give you look at doing snorkusectomy as well. The intake silencer removal is a cheap, easy and meaningful mod. It also makes it sound way cool, hehehe!