Originally posted by y2k4door
The Jap. spec engines are tuned to run on 91ish octane, so no problem there.
From what I hear, early WRX ecus are more flexible to lower octane gas. All JDM WRX's are tuned for 100 RON. To put that in perspective, Sunoco told me in an email that their 94 octane is 99 RON. So there is no pump gas available that a jdm ecu will be able to really stretch its legs with. I ran Ultra 94 with GTA fuel enhancer using a Rallispec tuned standalone. Rallispec tuned it off a base map for 100 RON, and they still had to pull major timing under load/boost. And an intercooler upgrade made me need more fuel. If you don't pick your mods very carefully, you will have problems.
If I could do it again, I would go with a USDM '02 motor/ecu only, as its completely legal that way. I would do an FP turbo upgrade, exhaust, and Walboro or Supra fuel pump, and run 1 bar, so it still looks completely stock, but delivers close to 300 hp. I no longer believe the stock L and RS trannies are a problem. My stock L tranny went on a turbo'd car pushing well over WRX power levels, and held up fine for the past year, and is still going. Its all in how you shift.
So, the WRX motor w/ecu will run you $2000. Turbo upgrade is $650, exhaust is ~$600-800, and fuel pump is $125. So that's a budget of ~$3600 for nearly 300 hp. Plus the suspension and brakes should be upgraded. And I wouldn't blame anyone for wanting to upgrade the crap stock seats. Even in this best case scenario, you're looking at minimum of 5 G's, plus labor will run 2-4 G's, depending. My advice is don't do a swap unless you have at least 50% more cash on hand than you think you'll need. Anyway, enough of my rambling, what do I know, I'm just a bitter Scooby driver who wrecked a wonderful EJ20 swap...