When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The general concensus is that they don't live too well with the STi- I previously had one on my WRX and was very happy with it although I do know the pro's and cons.
Consider: knocklink, AFR, EGT, charge temps, injector duty cycle, MAF saturation, MAP saturation, exhaust back pressure and fuel pressure. If you have all those covered enjoy.