i got a 04 sti with a 3" pipe, im about to purchase a 2.25 dual tip stromung axleback, power loss? fitment issues? previous owner had it on his 04 2.5rs....

 

I may be wrong; but I don't think that would fit. From my own personal knowledge, some people get a custom mid pipe.... or maybe even an adapter... Your best bet is to measure it and see if the wholes match for the bolts. As of power loss....I'm guessing it would since you have exhaust flow from a 3 to a 2.5 inch pipe...

 

[after further research...talking out of ***]