More power

Help Urgent - does get peoples attention :)
 
There are so many steps to getting more power, all a balancing act of air/fuel/tuning, and its limitless to what you spend and then what you need to spend more.  Do some google searches and you will come up with info from how to get power mr2 KOracing, or ats, or racerx and various others.  Each set up depends on drag or hill climb or racetrack.
 
Guys out there with way more experience than me, however my approach get your supporting mods first; upgraded fuel pump, fuel pressure regulator, fuel rail, throttle body, heat reductions, gauges (some sort of warning for when things start to go wrong), and dont forget about good brakes or upgrade so you can stop after you get excited pushing the limits.  Hi-flow maintains exhaust manifold, if you want big numbers you need another turbo, but that adds $1000s in exhaust manifold, wastegate actuators and other mods.
 
$1000+ on an ecu, $1000 on injectors/fuel rail/fuel pressure regulator, $1000+ cams headwork, $500+ on a tune, $1000 on intake manifold, $1000 misc supporting items, and you could push as much as 300-350 hp. 

My opinion, start with a decent ecu such as a Haltech, autronic, motec, ViPEC or Power FC. You will need bigger injectors (540s at least) for more than say 250-270 rwhp. In saying that a big jump in HP is not a great idea. As discussed you have to balance the car as a package. Brakes (at least pad and fluid upgrade), suspension, tyres, clutch etc. reliability is key so expect as you start to push an engine beyond its normal limits other things may start to deteriorate. As for hi flow I had a ct26 hi flowed by hyper gear that performed well.