I have an old nova 250 with twin 302 fords, 2 barrel carbs, supposedly 188 hp apiece, boat runs good, comes on a plane pretty quick, and the motors seem to top out around 4300 rpm with my gps saying 46 mph. what Im wondering is how much power wise and speed wise would I gain by throwing some say edelbrock dual planes on them with a couple 4barrels and maybe a cam upgrade? would it start drinking gas??

I'm not an expert, but I don't think it is gona drink more gas... 188 hp each is not much for a boat in this size. I think more powerfull engines will work more freely, or not as hard for a given speed, thus making the boat maybe a little less thursty... just my opinion based on my previous experiences...

Sounds like a good idea to me......

Old school caught my eye...my 02...heads won't flow..kinda remind me of the 70's...we spent alot of money and busted alot of knuckles before we started putting in BIG BLOCKS.......boat is perfect now....have FUN!!

I think the fords with the 302 4 barrels were considered 225hp, I know the 305 chevy's were 228hp, If your engines are in good shape It would be a good bang for the buck.

less the 5 mph
In my opinion

No matter what you do up top, you're still dealing with low-perf bottoms. Take care of that and you've got weak drives. Plus, you'll need to re-prop. For what you spend on getting 10 or 15 mph, you could trade up to a bigger, newer, faster boat- especially with the used boat market being what it is right now.