Does this change the sound of your engine......?

Rick32

12 guage is a little closer to stock than .410 or 20 guage.

If you're talking about Shotgun Mufflers, they will quiet the exhaust down quite a bit at idle and will quiet it somewhat through WOT depending on how you set them.

I like them. They take the bite off the idle and help stop reversion issues.

LOVE EM!
They are mechnically simple, NO air pumps, solenoids, wiring, nothing to break. They seem to be well engineered, and I've run my pair for 75+ hours in Salt water with 0 problems.
Hope this helps,
MD

Excellent product with simple design and installation. They do the trick at low RPMS's especially around the dock and in channels, etc. But, as you increase the RPM's, it basically riverts back to a full thru-hull situation. If you do a search on noise, you will find them mentioned in a number of threads.

Love mine too. A little quieter at idle and no RPM loss on top. The only thing I don't like is at idle they make a noise that kind of sounds like a valve tap as the metal shutter slams shut but its not noticable unless the engine hatch is up.