just put mine on about 3 miles ago,
it feels like it does have a little more power and better responce, but i have been driving around for a few miles on a leaky exhaust so anything that doesnt leak would be an improvment
i havent been on the highway but i will tomorrow and ill let you know, but it is a little loud, and it has a nice sound. i feel the quality is a+ being that im into the import car scene. i think its better quality than my 3" mandrel exhaust that i have on my turbo'ed infiniti and that exhaust is damn nice.