What is the average hp gain on a whipple supercharger 3300 on pump gas

The best person to talk to in depth would be Eddie Young if you want legit and honest answers .

I will very depending on the set up. EFI, Carb, Exhaust, heads, ect. Go here.

http://www.whipplesuperchargers.com/...7&DisplayCat=1

Get a hold of Dustin at Whipple and he will answer all your questions.

it is efi

i plan on putting them on big block motors that was built by innovation marine in sarasota florida. motors have around 535 hp now was looking to get around 700 out of them. i figured that putting a 3300 series on top of the motors would get me around 700 to 750 hp after tuning and what not

Those hp numbers will not be an issue with the Whipples.