godgirl, do the basic mods first, improve breathing by replacing restrictive ori filter element with aftermarket one, (eg. K&N) and improve farting by changing your exhaust system as gt_auto said...increase piping size to around 1.7 to 1.8 inch, using the header from the wira se also can, its pretty good, based on dyno charts ive seen....
stuffs like aftermarket spark plugs and wires you dont really need it now, it wont really make a difference, unless your old ones are already worn out :P only when you have managed to squeeze in more air and more fuel into your engine, then you can look into upgrading your ignition, otherwise an ignition upgrade on its own wont really yield any results...
happy modding!