Late last season I posted about finding a significant RPM loss on top end due to the Hardin Marine insert mufflers. No hard feelings to the supplier, just didn't work for my application. Someone recommended GGB's at the time. I'm looking at them on Ebay since their marine section of the website is closed to the public (apparently due to public incompetence). They offer a few different sport models that I am considering. One is 4" x 5.5" long and another is 4" x 8.5" long. Can anyone tell me the noise reduction difference between the (2) options and roughly the overall decibel cut with this type of insert? Also is anyone here a dealer that could hook me up with a set since I'd rather do business with a member here if possible. Thank you.

Video I shot last summer . Can you tell what one has GGB inserts and what one doesn't

He bought the 8.5" ones and cut 1 ring off.

He likes them and reports no loss in power wile it keeps the fish police happy.

https://www.youtube.com/watch?v=W2yNFX2olhc

The 5.5" performance model (slightly bigger inner diameter) will drop idle noise by 4-6 dB. at about 3 feet aft on a stroker small block with 4" thru hull exhaust. I personally took the measurements. These inserts did not affect WOT rpm unlike other inserts which choked the motor 300-500 rpm. Sound is better too.

The longer rings aren't required for his application and often becomes more of an exhaust real estate limitation.

Trash, you don't think I will get any additional noise reduction from the 8.5" over the 5.5"? I ordered the 8.5's tonight after the feedback I received today, but hell, if it was up to me I would leave them out altogether! Quieting the exhaust was cheaper than dropping $2k in wireless headsets so the ladies could talk while cruising....

I'm running side exits so I do have the room, I'll just have to drill my tips inside the boat before the internal flapper and seal with silicone.

To be honest for a 6.2 motor I don't think it will make that much difference over the 5.5. My concern with the 8.5 is fitting them. If you have the room to slip them in go for it. Take some before and after measurements and let us know. If you were installing for a BB the 8.5s would likely help more.

Some food for thought....there are other factors that can make the boat appear louder beyond the exhaust. My boat is WAY louder inside the cockpit with the bimini top up because it catches the sound waves emanating off the water and up, then reflect off the bimini into the cockpit. It is quite noticeable. Turn downs can help as well at idle.

Yes, I agree about the bimini. But I like to stow mine so I can run at higher speeds without fear of damaging it.
I only have a little space for the inserts so I have the 5.5" length GGB's. They mellow and reduce the bark pretty well for me.
My 10.2:1 383 stroker is deafening when compared with the 350 Mag it replaced. I think it's a combination of CR, cam, and the extra height EMI long tail risers.

I love to light it off at public docks and watch people turn around with that "HUH" look! That little boat?