QUOTE(ottox914 @ Apr 19 2007, 05:11 PM)
I made a similar kit with some plumbing left overs and a K/N filter, mounted directly under the engine lid grill, with no rain tray. I used a GTECH, not the most scientific of testing, and recorded an 8hp increase, and this was after 5 runs, toss the high and low, average the middle 3 runs. I was suprized to say the least. The problem I had was that it was so tall to get right up to the engine grill, that if everything wasn't tightened just right, not to much, not to little, I'd rock it right off the throttle body at an auto cross. Some side to side bracing would have helped.
I'm a carb guy, but when I put long manifolds on, it made a colassal difference in torque. That may cost some top end, but high ultimate speed is not what a 914 does best anyway. I think the benifit from this setup may come from the fluid dynamics at work.