Okay i have 23ft century ultra1 with a stock 7.4 330hp boat runs 67 with a 23p mirage plus. I was thinking of just getting a stock set of heads off a magnum motor so they are rectangle port so i will have better flow and adding a Cam, High rise aluminum intake,a bigger carb not sure how big i should go though maybe 750? And putting a set of headers on aswell. What kind of gains could i see from this? Or am i just waisting my time and money? Any input will help Thanks!

Basicly you will just be wasting your money. The bottom end of the 330 is weak. when I blew my 330 I rebuilt it with all ARP bolts and studs, 188 rectangle port heads, small cam, performer intake, roller rockers, 750 carb. Engine only made 400HP on the dyno but I have redline set at 4600-4800RPM. If you try to spin a 330 bottom end any faster you are asking to blow up your engine.

Ok i was kind of thinking that i would just like to get a lil over 70! Lol then in the next year or 2 im going to do a 502mag with a procharger Thanks for the input though!

67 with a stock 330 I would not touch it.

Try experimenting with some other props and you might be able to get 70 out of your boat with the 330, and save the rest of your money for the new 502.

I think what I did was a waste of money. Sure it made 400 on the dyno but in the boat I bet it only makes about 360-370 with Gil Manifolds. That was a lot of time and money for 40hp. I should have just got a reman 330 or spent the extra money for a crate 502.

I'm looking into the 496 ;-). If you don't venture to the 500+ci consider stroking the 454 if more power is what you desire. Seeing I would replace crank anyway if it were a cast crank????