I know a performer intake wont hurt mpgs,and they are much cheaper than the aluminum tbi intake.Also,a performer should give a boost in low rpm torque.I dont see were some portwork on the exhaust side will hurt anything,it should help with some extra power,and the millage shouldnt suffer much.Im thinking of a compucam.I been doing some research,and they say it really increases bottom end torque,AND mpg.The headers are coming pretty soon,i hope,along with a throttle body spacer,and a computer chip.