Anybody out there running Gibson Bullet mufflers on a 600cu/750hp NA motor? They claim no power loss, i'd like to hear from someone, before/after, did you lose top speed or not?

And DB test results.

I have not run Gibson, but have tried CMI's and GGB's. Neither effected speed/rpm in boat. I don't know about HP as no dyno done. However, neither of these were effective in meeting our noise law (90db) on my 598 N/A engine, 10:1. They do quite it down quit a lot but not legal.

I went from 113db to 94-95db.

I currently have downturns and are in the 80's.

Rick

I ran gibsons on my 650 HP blown 509's. We lost a mile or 2 per hour but the boat had a nice throaty rumble. Never pulled over by the LOTO Wp with them. I'd guess though we were over the limit but a lot less than many w/o mufflers.

I'd own a set again.

Hi,

I have two pair for sale...I used them for about two months and then sold the boat.

I noticed a considerable decrease in sound. I never really pushed the boat so I can speak about loss in speed or power.

Call me if would like to pick up a barley used set (fresh water).

Chris
323 864 8332

How much? clamp on or transom mount?

I'm not so much concerned about being right at 90db, I just need something to take away a little of the bark. My boat has a top speed of 122 now, if I put these on and it runs 119 I can deal with that, if it takes away 10mph that's a different story.

Ron Gibson= good guy.

And what diameter?

Just FYI, I have a set of brand new 4 1/2 dia inlet x 6 CMI Clamp on mufflers for sale. They say these will not affect your HP or RPM at all for up to like 1200 hp while the 5 inch ones are only good up to 525 HP.

http://www.custommarine.com/accessories/Silencers.php