I was wondering if i have a 5.7 2006 volvo and i wanted to go from 320 hp to 400 what would my problems be, I want to ditch the EFI go to carb. intake and exhaust go through the lower unit. And i want to keep it that way. DPS-A 1.95 Just want to see if this can be done. thanks for any answers.

383 stroker

Belt driven air cleaner….you’re not going to get 400 hp out of a 350
in a marine application without one

Your engne and boat are worth way more $$ in stock configuration. Save the $$ for a complete boat upgrade.

What about a stock rebuild with a slightly bigger cam.

20 hp?

Hard to break them… probably doesn’t even need a rebuild. Enjoy it for what it is.

If you upgrade the cam with anything that you will even notice in HP, you will need to get new a 5k performance exhaust system and find somebody who can custom tune your ecm for another 1-2k.
A cam, tune, exhaust might give you a 20-30 hp gain which equals 1-2mph faster top end speed.