I have a 94 21' Mariah with a 260 hp 5.7 Bravo III with less than 200 hrs. Has factory installed Corsa captains call exhaust. Thinking about finding and rebuilding a set of Vortec heads and swapping them and the intake and at the same time go to a better hyd roller cam. From what I have read, because it's a bravo III it already has a hyd roller cam. Looking for more power without killing the bottom end torque and fuel mileage. Boat is multi-purpose as a skiing / wake-boarding/ tubing etc. Would like to see a little more top speed (runs 57 mph now) and a better sounding idle for the party cove cruise through. lol. What heads do I look for and I'm open to cam recommendations.. Or am I waisting my time? Oh.. I was suprised to see that the factory intake / carb setup is a Carter AFB style carb on top of a spread-bore intake with an adapter.

Vortec heads are a 30hp gain by themselves.

I wouldn't. Ive messed about with small blocks with my previous boat... its not worth it.
For your boat. A cheaper option for top end is to get a standard bravo 1. You'll see a few mph
If propped correctly. That boat is perfect now for how you use it though.
Btw. You know a "few" mph more wont satisfy for long... in the end its cheaper to sell your boat and buy a faster one. This is just my opinion, ive been wrong before.

Stock out of the box Vortec heads and a LT-4 hot cam along with a Performer Intake plus a Holley 750 Double pumper will put you close to 400 horse turning 5500 RPM. I personally wouldn't do it unless you love the boat and don't mind spending $2500. You won't see much over 60~65 with the Bravo III but it will accelerate like a bullet. Switch to a BI and you might see 70 put you'll be sick as to what you loose as a ski boat compared to the Bravo III.

Don't short sell yourself...you have a nice rig there and 57 is fast.

I look at it this way...60 in a boat is like 100 in a car. If you can run 45~50 in a long distance cruise with 4 aboard you're ahead of most boats anyway.

Thanks, we do love the boat, and not willing to get rid of the advantages of the dual props for our hole shot and slow speed wake-boarding. I hate the stock truck sounding idle with open exhaust, and already have a good 750 DP on the shelf. The hotrodder in me finds it difficult to leave anything stock. lol. Probably wouldn't do anything til next winter as our boating season here in TX starts real soon. Explain what the LT-4 hot cam is ? I'm a Ford guy.

http://www.thirdgen.org/techboard/te...c-lt4-hot.html

It's the Corvette LT-4 grind. I like the Comp Extreme Marine roller series...with rollers you have to cam up more to get noticeable idle more so than a flat tappet because the ramps are smoother on the lobes. Go with the 272 grind for some rumpity rump but use taller exhaust risers to avoid water reversion.

The 355's I built made 421 horse with those cams and I'm putting a pair in my 255 Formula as I write this. The idle is barely noticeable.

What heads are you running? I thought about welding extensions on the exits of my risers so the exhaust has some more dry length. Not much room to add spacers under the risers, although I'm not completely against trimming the fiberglass if I have to.
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I'm running Vortecs with Comp HD Springs. Had to relieve the valve spring pocket for the larger diameter springs...Comp needle bearing rockers.

And just to clarify... You're using the LT-4 cam or the Comp 272 ? What ratio rockers?

Your 260 "may" have the flat "lowrise" intake. If so you will get a good boost by going to the iron version of the old Z28 high-rise intake (got mine at the Chev Dealer). I had to add different metering rods to the secondaries which I got at the Carborator Shop in Onterio Ca (they are on the web). I did rejet the primaries but only picked up 50 r.p.m.s on digital tach... a lot of work for not much there. I also changed heads and cams but it got expensive fast (times two as the boat was twin powered). The intake swap was the best bang for the buck. Picked up 400 r.p.m.s. and a lot of torque.