1991 toyota mr2 turbo upgrades?

[lilnuggy]

i bought my mr2 not that long ago and it appears stock 2 me. i was wondering what kinda cheap upgrades would get me the most horse power and along with those what else might need to be done to support them if anything. i was wondering about upgrading the turbo but not sure what a good turbo for this car is with good psi i still have the stock 9 or 10 psi can i put a bigger one on with out having to change a bunch of things . if so what would you recommend for a turbo as well as other nice upgrades .thanks guys for taking the time to help