i tried it on my old sonoma and it was good for at least a few tenths. and it looks like it will work with the sierra/ silverado too.

try this: take out the passenger side headlight, (just the top one shoud do). and tuck the lights inside. it will open up a cold air box and filter to the outside of the truck. try a befor and after and post some results. i will try it wen i get back from a short deployment. (the navy still has my soul) also they ( www.quicktimeperformance.com )should be close to finishing a set of headers and hopefully a y pipe w/ QTEC's.

 

Here's some pics of the ram-air I had on my Silverado.
Jim

 

koool, but this my setup is free and doesnt take any fab at all. just twist out a few bulbs, and right into the airaid cold air, 200-112 i think.