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?

I was suprised to see the gain myself but this is on twin 496 mags.
when I did the switch on my 290 with twin 454s other than a louder exhuast I did not notice anything else.

I went from open exhaust to the 6" version of the Corsa mufflers on my boat last year. I noticed no change at all except I like the sound level much, much better now. Call me old I guess. Corsa told me they would cause no issues up to the 600HP range.

I had changed them on my old 23 and I'll say they was defiantly a change in the sound. It was much louder. Loud enough that the wife really noticed and of course I got what did you do????? Speed wise no difference but the 23 was a real tank. I think your right the bigger HP's motors may see some increase.

verbi69 what kind of speed gains did u see from the raylar kit i have been considering the kit not sure if i want to spend that kind of money or just step up to twins
thanks john

Hi John,
My boat would run a steady 64 mph with a labbed Bravo 1 26 pitch and with the Raylar now I am seeing 70 mph on gps.
I have not run the boat with the labbed prop because I had taken it off and sent to to BBlades for some cleanup and rework.....so I expect to see another couple mph for sure.
I am also running the stock exhaust - no headers yet.
The kit is not cheap for sure and I had a professional shop do the install along with a full tune up like plugs wires all filters belts and impeller and drive service so the bill added up quickly.
I love my boat and wasnt ready for twins so there is no replacement for power....and this thing really works now.....there is no lack of power anywhere in the rpm range...it pulls hard.