you stated with just an exhaust your sti is much better than your mps that had lots of mods but than you say you only got a 5-7 kw gain and let me guess your exhaust was about 2k plus. the real truth should be about 15- 20 kw gain and with a tune the sti will only get 35- 40 kws at the wheels . which will be awesome for the street but with out forged pistons thats it. sadly your sti is no stronger than your mps engine be careful with tuning oh and who are you using for tuning