Well mine was on the car when i bought it, not had it rr'd. But I'm running that, ktec stealth with decat, cams and an rstuner remap. It feels a lot more responsive and quicker than my old 172 than just had exhaust and uprated panel filter and drilled airbox. So can't really comment on the difference as theres more to my new one than the old one sorry dude.
From what I have heard they are one of the best ways to go, and not the most expensive either, less than £100 for the whole set up I think.