GregP

If you have dry exhaust all the available "boat" style mufflers will be quite a bit noisier. I have Gil full-time clamp-ons, which I ran on the prior dry Gill exhaust and on the current wet Lightning's (water enters at the transom just before the tips, about 4 feet from the cylinder heads).

The same mufflers with the mixed water are much quieter in "perceived" noise. I havn't put the sound meter on them with the mixed exhaust, but they were 106 db at idle with the dry exhaust (about 3 feet behind the transom).

If you run dry exhaust I'd look at the Borla/car style muffler solution that Dick (Mr Gadgets) mentions above.

-Greg

Kokopelli

Can you install Shotguns on short tips. I only have about 1 1/2" past the flange to work with. Utah is starting to crack down as well - buddy got a $1000.00 fix it ticket last weekend and he was only 2 Dbs over- Ouch!!

Griff

Yes, I think you need less than an inch. They just slip over the existing tips and then drill a couple small holes and bolt them on.

Intolerant1

I run the Shotguns combined with internal baffles on a 330hp 454. Both bolt on from the outside. I think the baffles are Eddie Marine. They cut the diameter down to about 3" on a 4" exhuast. I lose about 50-75rpm. The Shotguns alone do not do much. Fortunatly, my exhuast tip are angled down and half under water at idle. With the shotguns, the exhuast exists completely under water at off plane speed. You can adjust the Shotguns so that they do not open all the way as well. A nice feature if your taking the family or inlaws for a quite ride.

BAD-HABIT

What about slip in silencers? I know cp performance and rex sells them. I think they are about $100. per pair....If i remember they reduced8-12db on a 500hp motor. With very compareable power loss. Very easy install and are considered "permenent" But they bolt into your tips and can be taken out in about 5 minutes if need be. Also because of their design they help with reversion problems.....

"Bad-Habit"

Waterfoul

I ran a pair of those CP Performance slip ins. Lost 3 mph on the top end and could barely hear the motor run at idle. Took them out after one run. I now run the Drew Shotguns. Have for 4 years. Have NEVER been pulled over. I have wired them all the way open a few times (they rattle a bit at idle) when trouble shooting (to eliminate the noise). Believe me, they DO take the bark out of exhaust noise. I've never db'ed my moter, but I KNOW that at idle, with them open, I'm quite a bit louder than 90 db (the limit here in Michigan). A few weekends ago I happend to pass right by a marine patrol officer on Mona Lake, probably 15 feet from him at 900 rpm. He smiled and waved. Later that day I ran into the same officer at Taco Bell (yo quiero Taco Bell!!!!). I asked him point blank if he thought I was too loud. He said no, he wouldn't bother me becuase I was not noticably loud. I'm running over 400 hp thru EMI manifolds with the tips under my swim platform, which is teak and slotted.

I think the key to not getting pulled over is to make sure the boat you are next to is louder than yours!!!!!!!!

Falcon

If you are running an Alpha or Bravo you can run the external clamp ons, such as the gil's, and put in silent choice type pipes. When the valves are open, the exhaust can exit through both the drive and the tips. The drive exhaust pipe also acts as a type of crossover and that also helps drop the backpressure. This has been tested and I wouldn't run clamp on or slip in mufflers without also using the prop exhaust too. You don't even need the cutouts and in Wisconsin if you have the cutouts before the mufflers (and it passes the tests with the cutouts open) it's legal. You are using the thru hub exhaust to bleed off the extra backpressure.