With the Evo X you can flash the ECU with the Cobb AccessPort Stage 1 map to bump up the power a bit. You can flash back the stock ECU map and the dealership can't tell you touched the ECU. The stock ECU runs very very rich.
And the for the exhaust, this sound good. Not sounding rice.
I am running a Perrin Stage 1 map. I don't have a dyno sheet but from the company:
My gas mileage is about 22 in the city and 29 on the Highway. It varies sometimes. I don't drive like grandma either.