What length insert did you use, and how did you like the sound. Any performance change?

im not trying to make anyone upset, but i have Gibson slip on mufflers and they slow my boat down 3mph. i have a htm ss24 with a 565 n/a and with out the mufflers the boat runs 101mph on gps when i slip on the Gibson mufflers the boat will only run 98mph gps. every time, its very consistant. but the noise is considerably lower. just my 2 cents, the runs were on the same day with temps the same.

I got the 5.5" sport. They sound good, deep rumble.
I had too many changes done this year to comment on the performance (need more prop with the -2 IMCO lower). The boat is not slower than last year though.

Since loosing a GGB and putting gibsons on my 1000 ish hp boat I have lost rpms and mph, might pull them off at hot boat to see if its actually the problem, Smitty
The good GGB'S ran same exact mph and rpms open vs with them on a few years go and I was running 99 mph at the time FWIW

Go with imco gattlins. Takes out the bark, leaves a deep growl and no performance loss. Highly recommended.

What are ggbs, the actual name to look it up

I guess it is these...

https://www.wr-products.com/pages/ggb-marine-exhaust ggb actual website... GGB Exhaust - Power by Design? looks like dealers only website.

Okay thank you for the information but those are all insets for the pipes-mufflers.Where are the mufflers for sale?

I think the idea s to not have an added on piece hanging off the back. do you have a straight shot you can slide an insert up the tailpipe? (sounds dirty!) or any hose sections inside boat between engine and tips? and are your exhausts wet or dry ? I only see inserts for sale, but this youtube video they are installing a muffler with case in the exhaust path inside. so they must be available somewhere. you could also buy stainless tubing and put inserts in and mount them the same way. I wouldn't want to do something like that to add on outside the boat though.