WRX_JB's 05 wrx Spun a bearing, Full build inc...

[Buster]

Let me try and help. I think I have just about every path covered with my own car.

1st mods should be a downpipe and up pipe. Both could be found cheap. Pick your poison with DPs they are all basically the same excluding the HKS. HKS is a great choice though. its very cheap and works very well.

Upipes are where most people make a mistake. Get a stock STi up pipe. They work great on all stage vehicles and can be found for around 75 dollars. Bolt right up and rarely leak.

Catbacks again you needent be to concerend with power, as long as its 3" for the most part you will be good. I have an IPP catback I'm selling for 150 in great shape.

That setup with an MBC netted me a 13.2 @102 which is pretty fast for a barely stg.2 WRX.

Tanabe DF 210s should be on for lowering you car, they are affordable, have great spring rates and are ore compliant for daily driving.

Also, pick up an STi intercooler and honestly with just those mods you wont even know it was the same car.