No one said you had to take all your shit out? haha I am trying to guide you with your setup not get you to build a drag beast?
You can make 400+. your going to need some parts to do it.
a Good turbo. (not ebay junk)
3 bar map
it would be best if you got some cams,springs,retainers.
LS motors hit a wall at about 350 with the stock cams for some reason. On my Borg warner 366 on the stock ls was 366whp at 18psi. on a large turbo. Granted it was really fast at 366 but it wasent 400hp.
Dont believe the “internet dyno hype”. One dyno number to the next does not mean to much.