I'm looking to install thru hull exhaust on my Formula. Any certain tips or kits that are recommended to buy out there. Should I just go with the 4" exhaust tubing and 2 tips? Do I need flappers over the tips? My last boat had silent choice installed on it so i've never messed with installing thru hull. Seems pretty straight forward though and I have lots of room to work with. My main concern is cutting hte holes in the wrong spots. Any sort of template available for Merc/bravo boats out there for sale? I searched the forums a bit and wasn't able to find the exact answers I was looking for.

Thanks in advance
Mark

Looks like it would work, 4" hole saw with a big ass drill. You can find stainless tips with stainless flappers at Eddie Marine or CP Performance. I have not seen a template, but there may be one. Take some good measurements off some other boats.

We probably have some tips you could use...

the mercury drawings come from crank C/L. You would have to pull the motor to use that.

You can look around you local marina to find a boat with thru-hull and measure from the top of the gimbal to the C/L of the exhaust. bravo dimensions are standard unless custom exhaust is used.

If you are planning on using silent choice set-up you will need to cut the "Y" pipe to the correct length to allow the hose connection to fit. Then you can take a piec of PVC pipe and slide it over the diverter to determine the correct position of the tip.

This will work without silent choice. You will have to cut the "Y" pipe and cap it with a 4" rubber cap and clamps. Then use the PVC pipe set up to determine tip position.

it will be super easy in your application.

the hose has a bit of "give" to it so you measurements dont have to be absolutely perfect. i measured the center to center on my risers to get the width and then held a straight edge at the angle i thought the riser outlet was to get my verticle location. make some pencil marks on the inside of the transom.

another thought is to cut your wet hose to length and install it on the risers (still use the center to center of the risers for the horizontal spacing) and then circle the hose at the inside of the transom. drill a 1/4 inch pilot hole from the inside and then drill with the hole saw from the outside of the transom.

i used a set of 4" stainless tips with integral mufflers and flappers. if you don't use the flappers and you have regular exhaust valves you may have a problem if you get some water in the pipes.

good luck and take your time with the layout and you will be fine. remember "measure twice, cut once"!

You're local! Send me a PM with some contact info and i'll get in touch. Thanks

This is pretty much what I had planned to do. Thank you for the advice!

Mark

Any suggestion on which flappers will seal the best so that water does not cause problems in the heads. This is a bone stock 454. I think this many be the reason I blew my last 454 in my Donzi. The boat had silent choice exhaust and I was out on a rough day in the ocean. Next think I knew the block blew a cylinder wall out and I was all done!

Without the silent choice, and no mufflers, you may want to cut below the water line.

Not my choice, but if you have sound restrictions, this way they won't bug you when you are putting around, but still sounds good on plane.

If you have the y pipe, go with the silent choice, best of both worlds (and you can shut them off when you see the cops)

i would also consider the postion IF you ever add headers to it.

Don't put them below the water line. That is a disaster waiting to happen. Gibson and others make through hull with mufflers that will keep you legal. I have Gibson clamp on mufflers on my 650hp 524 BBC and I have no problems with noise on rivers with regular Sheriff patrols. The higher the better!! If you plan on doing any cam changes chances are that silent choice is out.