Anyone have any experience with the above switchable mufflers? Just curious if they really work to knock the db down to a legal level. They almost look like a Corsa silent choice but there's nowhere to redirect the exhaust. Any comments would be appreciated. . .

I had them on a 500efi. They work great and will get you to a legal db.

I have them on a 502 Mag. They do a good job reducing noise. They are advertised as being ok to run quiet up to 3500 RPM but I only use mine at idle, When first installed I was running them quiet around 3100-3200 RPM , when I opened them back up the boat gained 100 RPM without touching the throttle. That tells me they are pretty restrictive, which is easy to see if you look at the design. If all you want is quiet around docks,ramps, marinas, they work great. Also if you get them when installed make sure the solenoid is on top or they will blow some water out the shaft that runs through to the butterfly.

Great thanks for the info. So when fully open there's no restriction?

They're not legal in some states because they are switchable, I've seen the solenoids burn up on several sets with minimal use.