Aqua Power Ltd gives a full satisfaction guarantee, worth a try.

It really is amazing to me, how many of these GGB users are claiming no perceptible loss in performance....doesn't seem possible to me that sticking a glorified cork in your exhaust pipe wouldn't diminish performance. Its crazy that Arctic is pushing 1200 hp through them and not losing any RPM. Maybe there is such a thing as a free lunch!!! Would still like to here from someone who has actually been using the Aquapower. The GGB's are a reasonable price, so I'm probably going to give them a try.

In back to back testing with my 1050 hp pulley/around 13 psi boost I saw 95-96 mph at 6200 with or without them. It actually runs much better at idle and low midrange with them on as it dampens the exhaust pulses a little or something. Now the Gibsons, thats another story although this is a couple years since testing the ggb's, seems to have lost 400 rpm's of top end with the Gibsons but something else might be going on, will be testing by end of Aug and will know, Smitty

Which style were you using of each? On the GGB site they only rate the clamp on to 800hp.

A few years ago Merc 1075s were tested by the field engineer with and without Aqua Power Mufflers and got the same top end rpm and power either way. It can be done, I was there.

Mine that I had were the "old style" clamp on ones they used to build before re-designing them BUT in recent emails with them Graham told me that he would make adjustments to the baffling (I think more) if he built me a new set to acct for the extra hp , they still custom build most sets anyways and will make adjustments to them to suit the application, Smitty

I have used several sets of GGB's in the past and can't say enough good things about them, even though I don't care for mufflers (as an engine builder, I want to hear them) I've put them in engines as big as 800 hp without any loss of power or speed. I don't recall the exact name of them (I have it at the shop) but they actually replaced the tip in the transom.
Eddie