I found this Greddy T67 Turbocharger Upgrade Kit for the Subaru Impreza WRX Sti. The site PlanetPerformace.com has it. It's $2800 and says it will increase HP by 45%.
300 x .45 = 135
300 + 135 = 435
Does 435 HP sound a little to good to be true? Anyone know anything about these turbochargers? Is it a good idea?

I don't know if anyone has even put one of those on a USDM STi yet. You will need a good tuner for sure