How much NOS?

[Shaggy]

I wouldn't go any further then 150 at first the pistons will take more but with the dual plane intake you are asking for trouble spraying more then about 150 without VERY closely watching your mixtures. if you had a single plane or that intake distributes the 150 shot VERY well then i would go no more then a 200 on that intake and 250 at the very most on a single plane the 250 will be severely sstressing the whole motor... assuming you are making 300 plus 250 put you at 550... more then enough to split a stock block and so on down the line. The HP level i am talking about is actual HP gained not HP rating by the manufacturer.