Well ive installed intake, headers, high flow cat, and exhaust, and new spark plugs and 10 mm wires, what else could i do to improve the performance in my 98 civic ex. thanks for the help

 

if you're sticking with the bolt-ons, Throttle Body/Intake Manifold would be nice. Short shifter/poly tranny bushings are awesome IMO, it dpeends what oyu want. N/A build? Some sort of F/I?

 

Adjustable fuel-pressure regulator, hi-flow injectors, LSD, lightweight 16" rims, 205/45-16 UHP tires, ceramic pads and slotted rotors all around, braided stainless brakehoses, adjustable anti-swaybars, strut braces, poly bushings, adjustable coilovers and shocks, short-throw shifter, and a HP clutch.

 

^ LSD would be sick, so would a stage 1 clutch, some suspension upgrades like you menitoned, some nice 16" wheels, and an awesome brake setup would be nice, but with just I/H/E theres no reason to be supplying more fuel. You're not forcing THAT much air into the engine. You'd end up running rich...thats why people don't re-tune their ECU with simple bolt ons. The stock ECU should be able to handle the bolt ons.