I just installed a cold air intake for my 3800SC. This is courtesy of a thread from Darth Fiero ... link below.
I was luck enough to find an intake duct from a 4.3L V6 Silverado pick up and bought the RU-3130 air filter from O'Reilly's Auto. I had a discount coupon for O'Reilly's so the parts total was only about $50.
It is necessary to cut the Silverado duct roughly in half. The end opposite the bellows end can then be clocked into position to fit the air filter and also to use the end to clamp to the remaining end of the bellows portion. The only thing that I did differently than Darth Fiero was to bolt a section of aluminum stock to the chassis and then clamp the other end to the duct. This was done to keep the air filter from bouncing around, but due to the tight fit in that area this step may not be necessary.http://www.fiero.nl/forum/A...130314-2-118267.html
Here is the install showing the bellows end of the duct connected to the throttle body.
Shows where I mounted the IAT. No mounting boss necessary ... just bore a hole and the IAT threads tightly into the duct.
Shows filter located inside the wheel housing and behind the wheel well liner.