I had my Evo 4 at a rolling road shoot out and it made 296bhp, the car has a full HKS exhaust, decat pipe and Racing suction kit, I fitted these myself but the car has not been set up other than whatever tuning Mitsubishi do in the standard service. There was also an Evo 5 and an Evo 6 there, both these cars had aftermarket air filters and exhausts fitted and made 333 and 341 bhp respectivly. I know that as standard the Evo 5/6 has a fatter torque curve than the 4, why is this?, is it just down to fuelling or are there other factors? Basically I want to know if I can bring my car up to 5/6 spec without major surgery, if so what do I need? Another thing is that my car made 257 lbft of torque which is a little less than standard, is this common for these mods or does it look like my car needs tweeking a bit to get the most from these mods.