On my 36 cat what would be the the best way to meet the current 90db. stationary test? 525 Mercs with the standard Nor-Tech exhaust. Thanks P.S. On my previous boat with a similar style of exhaust ( just smaller diameter), the CMI clamp ons got my 496's to 88db. at idle.

May want to read through this thread Chuck. Also, Wiggler is doing a lot of testing of Nortechs with different muffler combinations, so it might be worth giving him a call.

http://www.offshoreonly.com/forums/s...d.php?t=106039

thanks John

GGB makes the only 6" clamp on extreme right now. will probably bring you close to 90, they also have a new 6" insert that I think works and looks alot better, that is 19" long. I'm assuming you have the wet cmi exhaust . no angled water dumps at top corners. CMI has a new sound elimination system but requires all new tailpipes and they have to install it and is very expensive. I would try the 6" inserts first. Nortech is working on a retrofit turndown for higher hp applications, but a 525efi should be around 100db;s open ggb's will drop 10-12 db's.

thanks wiggler