Rippem

an hour at most to remove the under-platform enclosure.

20 minutes if you have a second set of hands to hold the wrench on the inside.

the two brackets between the drives are thru-bolted, w/ nyloc nuts no less.

I did it alone with some ingenuity.

Rippem

you guys are making this waaaay too complicated.

#1. Corsa transom-mount mufflers have taken the place of the silent thunder box for the muffling of the "thru-transom" exhaust. This is now standard.
See my post above, it's most likely about $$.

#2. a "diverter" or "switchable" system (Corsa's version of "silent choice") downstrem of the risers is an option...just as it has been for a few years now.

class dismissed!!

4mulafastech

Hang on, teacher, got a question. Is there any performance advantage to switchable system? I believe they all have the Corsa mufflers. If I understand correctly, with the switchable system "open" you get flow through the transom and the hub. This is just like it would flow/sound with a non-switchable system. So to me the only advantage of the Captains Call is you can "close" the through transom exhaust path and force all the flow through the hub to get reeaaalllly quite. No performance advantage.

Rippem

in terms of performance there are only disadvantages to be had...
if you don't use the system responsibly.

#1 Operating the system "closed" (ie: thru hub) there is a relative loss of HP (on a performance oriented engine) above say 2500-3000 RPM.

#2 There is a greater risk of reversion at the afformentioned RPM and above due to the limited flow, bends and turns of the "wishbone" pipe that directs exhaust (and the water) to the transom assembly. The relatively small diameter of the exhaust bellows, and the small passage in the drive also contribute to this.

exhuast will attempt to find the path of least resistance.

Therefore, in my experience, in the closed (thru-prop) position...there always seems to be some leakage past the diverter to the thru-hulls (10-20%).

The "open" position (thru-hull) is more of a sure thing (damn near 100%) as it is the easiest path for the exhaust to take.

you get extra credit!

Magicfloat

Cliff's notes on Exhaust 101. All 06 Fastechs have thru hull exhaust with Corsa Mufflers as std equipment. Sound is about the same as the previous Silent Thunder but without the extra weight of the water in the old pan. It is a nice throaty rumble but legal in all states. As an option,Corsa Captain's Call,an electrically switchable system with the Merc Y-pipe that sends the exhaust thru the prop for quiet opertation like a family boat with normal thru prop exhaust. But as Rippem said,there is some leakage around the valves and a little will leak thru the mufflers,no big deal. Downside of Captn's Call? Cost#1,Illegal in many states #2. #2 is not a big deal,haven't heard of any tickets for it but is is on the books and could at some point be a problem. Bottom line if you like a nice throaty sound that is legal,order the boat standard. If you want the option of making the boat quieter as conditions dictate,spend the money on Captn's Call.The only performance decrease will be when you close it up,but you have the switch at your command to open it back up. There will be a test later for extra points

Rippem

Robert, does my post (#4) seem reasonable to you?

and I forgot to mention the potential cost of warranty on the enclosure if it splits/cracks/delams.

take a look at my '06.

Magicfloat

Post #4 makes sense with one exception. Formula is not particularly driven by cost savings,if they were they would not be Formula I think that since so many 353/382 boats were ordered with Stellings where the pan would not fit,and the knowledge that so many owners were removing the pan anyway made them go this direction.Silent Thunder was a great idea years ago when it was so much better than a bolt on swim platform,but times have changed and Formula has changed with it. If anybody wants a 2006 with the pan,call me,I have lots of them stacked up from customers that have removed them,but I doubt I will have many takers. I applaude Formula for the change,it was needed and they stepped up.

4mulafastech

Thanks for clearing that up guys. I'm new to this picture posting but will see how this goes. Should be a picture of the stern of a 292. Took this picture Tuesday at the Formula plant.

4mulafastech

View of a 292 under construction. You can see the Corsa Y-pipes.

4mulafastech

Better view.