Recently I was asked for a recipe to take a 1991-1995 Toyota MR2 from bone stock (160whp) to 350whp on 93 octane pump gas. This is more than double the output of the stock motor. Believe it or not, it's possible. Here are the parts I would recommend:
GT3071R turbocharger kit
ATS rom tuned ecu
550cc side feed injectors
Walbro fuel pump
170 degree t-stat
ATS modified fuel rail
This is available for as a combo for $3750 on our site
Open element air filter - Apexi, or K&N. Do not use Blitz or HKS foam filters. They degrade rapidly, do not filter or flow well
ATS throttle body inlet - 91-92 only, the 93+ already has an ample sized inlet.
3" exhaust - the Ebay ones flow great, but tend to drone on the freeway. Berk is better about drone, but twice the cost
GSC/HKS/BC 264-268 degree cams
ATS adjustable cam gears
ATS Side Mount Intercooler with fan and shroud kit - I would prefer to use the top mount, but I don't think I can squeeze the stock AFM in there. Hopefully I can update that soon.
APexi AVC-R electronic boost controller. As far as I know this is the only boost controller that offers boost versus rpm control. Under normal conditions we limit all of our pump gas builds to 17 psi, but there is a small loophole we can exploit. The knock limit of the 3SGTE is basically defined by the torque curve. Most of these cars hit peak torque about 5000 rpm. We use the rpm dependent boost controller to raise boost a couple pounds after 5000rpm to keep torque from falling off. This in turn raises the high rpm horsepower substantially.
Total parts cost is about $7000. I have done this recipe many times over the years. The worst I have seen from this is 330whp and the best I have seen is 360whp. Now, if I had a little bit more in the budget the first thing I would change is the rom tuned ECU, I would swap that for a EMU and the next thing I would change is the fuel system, I would run a top feed rail and 1200cc top feed injectors. By switching to these items you open youself up to the possibility of E85 and lots more horsepower in the future.
Additional thoughts: The cost of a new AVC-R and a rom tune is actually higher than a EMU with the rpm dependant boost control option. The catch is the EMU will require some tuning, but I think the cost difference even after tuning would be about $400 higher for the EMU.