Just would like to get some thoughts on a large 4in intake which would be a warm air set up vs a 3.5in cold air set up.

3.5 cai would be the factory set up that the box was modified(like some of the other members did). But the real restriction would be in the filters...I beleive K&N rates them about 250cfm each. From my caluations, I need atleast 850cfm. Could go no filter ubt really dont want to.

Warm air semi short ram, could be get 4in set up(something like what hawks has for the LS1) and then the cone filter. At that point I would be able to get all the cfm need but warm.

In a perfect world I 850 to 1000 cfm cai, but really difficult on our tpi cars

In the majority of cases, a slightly smaller CAI system will make more power. But something like a stock single snorkel paper filter vs a 5" open element K&N obviously won't.