After searching, I have been back and forth on what clamp-on mufflers to go with. The engines are N/A Sterling 650's. CMI E-Tops, with 4" tips. I have 2" of clearance betweeen the swim platform and the tips. and 2.5" of clearance between the outsides of the 2 centers exhaust tips. I have heard great things about the CMI Sound Elliminators but Gibsons and EMI look to have a good product also. The Boat is a 2003 Donzi ZX. Thanks

I also have 645 H.P. Sterlings wtih CMI elbow tops, semi-dry exhaust. Wicked sounding, but just too loud. I was able to get 4.5" GGB Extreme clamp ons from OSO Member Lofty while they were available. Sounds great and think there may actually be a little more low end torque, no loss of top end.

HPI is the way to go.Works great even on 1200 HP +

Are you trying to meet any noise limit or just lower it some?

If you are not trying to meet any requirements all of those you mentioned will help cut your sound level. Meeting a noise limit is another matter!

Rick

I have installed several sets of the GGB mufflers and have been VERY pleased with them. They really cut down on the noise level, but did require some fine tuning of the EFI at idle because they richened the motors a little. The motors were Young Performance 750 EFI's.

No noise limits, just trying to tone them down a little.

I wish we could still get them, it is a great product.

sorry, but hpi's will not get you legal on a 1200hp blower motor, I tried them and they will knock off 10 dcb's got my 1150 nortech's down to 100dcb's a long way from 90 dcb limit., go with turn downs , only way to actually get legal and not chock motors

Dude, give me a call!!

do the turn downs sit under water when docked or just above the water line?? how much ?