Unichip Headers-Exhaust Air İntake Port-Polish Piston Those should improve throttle response and give you more power. Make it real pokey. That's about it though. If you were looking at aftermarket internals there isn't too much. the 4AGE motor is the one that has a near unlimited supply of performance parts for. Jason (rollamods) might be able to help you more, as he and his brother (MAP81) are close to walking encyclopeadia's on 4AGE, 4AGZE, 4AFE, 4AGE Silver and Black 20v, 1zz etc. ;)