Originally Posted by kpluiten
Why not look at an EJ207 swap? The EJ207 is the STi motor for the rest of the world. It is a semi-closed block like the USDM 2.5, it can have a twinscroll turbo (Version 8 and above), AVCS, big port heads, etc. It also spins to 8500 with ease, day in and day out. The 2.5L... not so much. It's a fantastic motor, perhaps the best overall EJ built. They also are WAY less prone to piston failure like the 2.5L. Best yet, EJ207's drop into the 02-05 WRX's so easy; they are nearly plug and play. No joke. Do a bit of searching in the 2.0L technical forum and see.
You can get a FULL EJ207 swap with the STi 6MT trans for $5600-$7000. On the higher end, they include the Brembo brakes and STi hubs/axles/etc.
This is the ^ BEST ADVICE
^ I have read so far...
I have a 04 ej205 2.0 WRX motor in my 02 WRX Wagon with 310whp at 21psi. That did not take much:
-WB Fuel pump
-Full Exhaust collector porting and flange matching to the turbo
-TGV Delete & manifold spacers
-Process West TMIC
-ebay 2 core Rad
......this is all on a ruff tune, Id more then likely be 325ish with a cleaner map
Like others have said the 5 speed transmission is a major weak point above 300whp ( unless your not planning on diving it to ever see it to the wheels
) . So the solution for that is like most do, a 6 speed or get a built trans either used or new. Either way your looking at $3-4000 done right. I got a used PPG 1-4 helical box and had it torn down cleaned inspected and converted it all to 411 for a total cost of $4100, including the JDM STi v4 front diff.
Im planning on doping in the v8 ej207 long block I have in my basement this spring and bumping up the injectors and turbo to a Blouch 18g-xt-r. With a new tune I'll be in the 425whp area at the right boost.
an ej207 would be the least money spent at a machine shop. Otherwise its getting a 2.0 or 2.5L sleeved, maybe a 2.2L if you can find one. Along with that you will need to build the heads if your not going STi heads with AVCS, and even then cams and bigger valves would help alot in the mid-high RMPs where your at full boost.