Out of curiosity, what color did he paint the car? Is that a subaru blue?
And whats wrong with intake and exhaust? Its not forced induction, its the first place to start even with NA cars I thought...But besides that he could do lightweight, underdriven pulleys...I think their might be some piggy backs for the ecu that give you some power...then there always a lighter flywheel, which will speed up shifts and let the car rev faster. You could get head work done, port + polish, 3 angle valve seats etc...headers, but you don't seem to want to do the exhaust. YOu could try the unheated TB mod people are talking about. Lighter wheels/tires lighter seats, hood, remove spare tire, remove sounds insulation, just start taking things off the car until it doesn't run anymore, when you hit that point, put the last thing you took off back on the car, and viola, your car will be lighter, hence faster, and it will still have everything it needs to run!
Micum
