Do mufflers rob speed?
 

On a 496 HO silent choice exhaust would the factory installed mufflers rob the boat of any speed?
I dont know what type they are but only know they came from the factory with them. They have the rubber flaps on the inside and a bolted plate inside.
Any input would be great...
thanx

Just removed mine from my boat.
boat has twin 496 mags,removed the corsa muffler tips and installed corsa straight tips,boat sounds alot better and picked up about 300 rpm at wot and seeing 3 mph increase on the speedo.

Wow....thats some nice gains with no major cost involved!!
Mine has the rubber flappers outside not inside like my first post says...typo there.
There is a metal plate inside that looks like it might be held on with the bolt.
I would like to install the angle cut tips...is there any chance that water can get into the exhaust without the flappers and that baffle plate inside?
Thanx,

Doing some research the mufflers I have a Corsa.
Do these rob power??

The angle tips will have internal flappers. The Corsa pipes help divert any water that gets in by dumping it down the Y-pipe instead of up and over the hump. Do it, if nothing else your motor will sound better and you still have the quiet mode for when around the old fogies.

LOL....I like your thinking...I was afraid of reversion.......
I recently had the Raylar 525 HO kit installed and there is definately a meaner growl to the engine....
I want to let this thing breathe as freely as possible.
I will be looking for new tips....
Thanks,

Hey boatnt or any one eles that might know, would this work on a 2001 pq with twin 7.4 mpi with silent choice? I know boatnt had a couple 29's just wonderd if you did it to thoses boats or if it is worth it? or what is the best option? right know i have the flaps on the outside too, i thought straight tips whould at least look nicer and maybe sound better to.

your boat does not have corsa mufflers,you have straight tips with water shutters in them so you dont get any water reversion,your good to go.

Just curious is anyone else has made the switch and seen this large of a gain? 3mph seems like a lot? I'd consider the change with that large of a gain.

Im going to do this...Do I have to drill new holes in my transom if I stay with Corsa?