Put 310 Merlin III's on my stock 420 bottom ends last year. Did the roller cam swap same time went with Teague stage 1 (Andrews billet core). Topped em off with Merlin marine intakes and 800 quick fuels. The butt dyno definitely approves! Good luck with your build.

Thank you all for your comments so far. I'm going deeper into this thing. This past weekend I braved removig the lame ass wrap the previous owner installed. I didn't care for the design and it was all knicked up and pieces were coming off. Before last season I used silicone to cover up some of the blemishes. I was surprised and pleased to see what I found underneath. Here a a few pics. Starbard side is 3/4 done and port side is just started. I feel like I have a new boat again. Also going to remove the stock swim platform and go with aluminum tube flatform. Taking a saw to that this weekend.[ATTACH=CONFIG]513957[/ATTACH][ATTACH=CONFIG]513958[/ATTACH]

Awesome!!

I've searched the net but can't find any specifics on the Corsa Marine Boat Quick Quiet II Exhaust Tips and 500-550hp application. would these tips work ok or are they restrictive? The have the baffles inside, here's the link of what i'm talking about.

http://www.ebay.com/itm/Corsa-Marine...-/181297873746

Honestly I would avoid this type of switchable exhaust. All bets are off regarding possibility of reversion.

These aren't switchable, they are just the tips with built in silencers. I liked the sound volume I used to have when the exhaust came out of two 5" holes from withing the fiberglass swim platform. I'm afraid straight tips now along with an aluminum bar swim platform is giong to be really loud.

I've debated keeping the stock setup to reduce cost but I think those two 90 bends would be pretty restrictive on some new HP engines
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Oh I see, just assumed you were taking about captains call. Yeah it will probably be quite a bit louder without that swim platform you had before. Have you asked Madera about these? I wouldn't even entertain keeping those 90 degree bends. Go straight, it will be well worth the effort and expense!

Not yet. I'm talking to my builder today to pull the pin on the heads then I'm calling Bob for the cams.

Is there a way to get two more exhaust holes going out the back for the inboard pipes? That would help considerably. The Quick n Quiet setup was configured a couple of ways - the original QnQ used a Y-pipe that sent the exhaust both out the transom AND out thru the prop. They combined this with a set of muffled tips that had baffles built into them. The idea was that excess backpressure above idle would be sent out the prop in addition to the tips, and help quiet down the exhaust. A friend of mine had these factory equipped on his Powerquest that had the HP450 in it - which was essentially the 454-based HP500. He removed the baffled tips because he wanted it louder, and saw no speed increase, so that tells me that there was probably not excessive backpressure with this system combined with the HP500 carb cam, Dart intake, Gil exhaust, etc.

Another version of this system, called QnQ Plus, made use of a switchable diverter that allowed you to send all the exhaust out the prop. When used without muffled tips, it was called Captains Call.

I think these were actually the type of tips that were used with QnQ:

http://www.ebay.com/itm/CORSA-Marine...81297873746%26