performance upgrades
 

just bought an 2003 gt convertible.30k i owner.previous owner did bbk long tube headers,bbk "h" pipe flowmaster exhaust.bbk cold air intake,throttle body spacer,underdrive pulleys.was wondering what could i do next.bottom end it pulls great,top end seems to run out of steam.

Changing the rear end gear ratio will give it more snap.

+1, increasing the gear ratio. It's a great cost-effective way to increase performance. You may want to replace the axle bearings at the same time.