Had Pantera in Miami install a set of GGB Extreme Variable Mufflers while they were putting in a 525/xr in my 28 Pantera. First of all they really look great.
The sound is much nicer than the open pipes I had with flappers. I could not speak to anyone on the boat without yelling. I also did not want to quiet it down too much either. It's a perfect nice low pitched tone without the harshness and noise. Also not quiet like a corsa or typical silent choice system.
After a few hours on the water the sound does not wear you out.
One of the best additions to my boat yet!
Greg

Troutly,
Will have to see if I can get a decibel reading. They have an internal rubber flapper with a spring that connects to the flapper and pulls back. I did remove the springs because I could hear them flaping. Graham at GGB says that will increase sound level by about 2 decibel.
Greg

Troutly,
Can you fill us in on what happened, sounds like it didn't meet your expectations. If you don't want to reply to everyone, please send me a private message. I am interested in knowing before spending dollars...

Thanks,
Rick

Looks great, still contemplating which ones to buy. I too am curious about Troutly's experience with HPI.

Here is some of his thoughts.......

http://www.offshoreonly.com/forums/s...ad.php?t=56911

Bought a UEI decibel meter to check the sound level. Will have it by this weekend to post db results.
Greg