This is what i built for my 08 GXP. there is now a plexi lid on it and sealed with foam. IAT's read anywhere from .2 to 2* over ambient. Note this car is the 5.3L V8 and not the supercharged 3.8 V6 so the colder air provided by this solution would equate to more HP over an open cone for me as this intake flows more than enough for my current level of mods. It is also built with expansion in mind to a 90mm FAST intake/TB and larger MAF. Everything inbetween is 4". I simply change 2 couplers for the MAF and go.
For those 3.8 SC owners desiring this solution it can be built by yourself for about 200 bucks counting welding supplies, sheet metal, and insulation, filter, couplers, etc.
