that may not always true. i believe it was Kenne Belle who discovered that a 2V with a blower, cams, and ported heads actually made more power than the same setup on a 4V with cams and ported heads. it had something to do with one big single exhaust valve being better in forced induction applications than 2 small exhaust valves. i wish i could find the article.
I am leaning toward keeping the GT and swaping in a 4v. it would be a lot of fun staying stock looking and N/A with a built 4V... The look on some LS-1 drivers faces would be worth the price to swap to ported 4V heads with custom cams
are you considering 5.4? or 5.0 BB? boss330 is against either stroking or BB sleeving BIG hp.
i believe i have adequately demonstrated how 5.4 can fit under a stock hood. it's simply an intake matter. i am going to construct my own intake when i change to 4v. seriously look into that. short radius 2.25" section tubes are enough. my idea is to use the navi aluminum part of the intake for the ports and bolt SS tubing to it. when the time comes i am willing to help others.
p.s.the KB blown 4.6's numbers that get thrown around for 3v are ok, but just ok. every time you meet a blown LS you will lose. 5.4 3v can be done for less, and cams are available now. get some cubes guys. then blow it if you have to. right now(in it's infancy) whipple charged 5.4 3v's are exceeding 415 - 425 rwhp with blower and tune in an auto truck.