I could have sworn that I posted that in the Renntech Airbox thread but when I checked, it wasn't there. Maybe my post didn't go through....
Anyway, as for power, seat of the pants would tell me that acceleration is somewhat improved. At WOT, it pushes you harder into the seat. That's the first thing I noticed. (Either that or the need to feel something cause of the expediture involved
). It wont bring you to 911 turbo territory but it accelerates noticably better. I didn't notice a difference in sound the way you would with a K&N FIPK (not just a swap in filter element). But it sure does make the engine bay look nicer!
The airbox is noticeably larger. If you compare the two, the MB airbox has various angles in the cover which make the total airbox volume smaller. The Renntech airbox is thicker and the cover design gives it more internal volume.
The airfilters it came with are ITGs, by the way, not K&N.