[Shane@DBPerformance]

It is not hard to tune around some overrun, it's a very minor problem, but vendors love to sell parts you don't need. You can use injectory latency, the MAF scaling tables, and your stock O2 sensor(if it's actually working, it often isn't on 1Gs) can trim it a great deal. I usually don't have any trouble getting the fuel trims within a few percent using injector latency and the MAF table. If your O2 sensor can't adjust enough at idle/part throttle to get the A/Fs back to 14.7, then your tune is off, you gained a boost leak or something else is wrong. I run my 1G in open loop with no O2 sensor at all, with a stock FPR and 255HP, so that I can actually run it leaner than stock for better gas mileage.

Both me and C3LICA have stock FPR, stock fuel lines, factory internals. C3LICA's put done in the 450s AWHP on our dyno and would probably be in the 520-535 AWHP range on a Dynojet. Mine put down in the 480s AWHP on our dyno and 563AWHP on a Dynojet.

DSMs are American cars, so it's kinda hard to make a JDM one.

Avoid Southbend clutches.