Has anybody put the clamp on hpi's on the existing tips that are on the boat after the silent thunder has been removed on a formula? There is only about a 1 1/2" of tip there and don't know if that is enough to clamp on to, Thanks, Jeff

I am in Minnesota. I have a stock Mercrusier 454 (7.3) carburated. I think it's 310 hp. It has a standard Mercruier exhaust with cast iron manafolds. I just talked to GGB, they have an additional muffler that clamps on to the tips I installed. All together, I'd have 12' of muffler sticking out. Really ugly. Anyway, I have no choice because the pipes behind the transum don't have enough rubber-hose length to accomidate an inline muffler. If I had 8" of rubber hose, I could install an inline muffler.

This is getting pretty ugly.

formuladude312

I didn't want to risk it. There was just enough room on the tips to install ruber flappers... not enough room to install clamp on mufflers IMO. I did not want to loose them at $400+ each. The old formula tips came off easily using a 2x4 as a prybar. Just drill the holes using the template and mount the new tips. They sound great....

Powerguy, Thanks for the reply, I have the rubber flaps on there now but by the looks of the pics on the mufflers it looks like i would need a little more tip to mount them on, Did you go with clamp ons or did you get bolt thru? Did the existing tip holes match up with the mufflers? And how much noise reduction was there and or speed or power loss? Thanks, Jeff

You can come out of the tips and make a 90 degree straight down and end 1-2" below the water line. At idle you will be bubbling up thru the water and at speed the ends will be out of the water. This might be the only way to beat the 4'-4' idle noise rule.

Great suggessions. Thanks everyone. I'll let you know what I come up with and report the db results. Thanks!

Tom

I did this on my '83 formula with 350, before installing silent choice. It worked well. I used old flapper mount to hold SS springs on PVC elbow pushed into 3" tip, then PVC about 6" below waterline. Drilled and tapped 1/4"-20 on side of drive mount, (non-critical location). lower 1/4-20 SS screw through pipe into tapped hole on ring. low speed, quiet, once on plane a lot louder, but not as loud as straight pipes. Used this system for 1 season. PVC held up well due to water in the exhaust stream. Lots of funny looks from "other" performance boaters with Silent Choice. BUT IT WORKED. Almost as quite as "thru the prop". Cost about $20. Maybe I should have painted the down pipes and elbow black?

I know you can get "custom" tips that have mitered elbow pointing down, how far they reach is up to you. Saw this on a spanking new Sunseeker with twin BB. I like the PVC approach, it solves the problem and doesn't cost hardly anything. This "cheap" solution sort of "tees off" the guys that want to "punish" you into some expensive solution. I chose Silent choice later for resell purposes.

I have something simular on my boat. I put a solinoid valve on my oil cooler. When I want, I can turn the water on and give the headers an extra shot. I did this for cooling, but it does quiet things down a bit. I used 3/8" line for my set up. If you wanted to really quiet things down, you should up size that to at least 1/2".

That's it exactly. That'll fix them sound b**tards.

Only word I have is TEAGUE

Love mine, however as far as actuall dB readings I do not know
But what I do know is that even with them open I am alot quiter now then when I had silent choice. Closed they are extremly nice n quiet



ST-450 Switchable Exhaust Muffler System

The best silencing tip on the market today. Meets most OEM and MerCrusier standards. Electronically actuated (no more pneumatic pumps!) allowing a 15 to 20 decibel drop at the top of your fingers. Flow rate is unrestricted in wide open position for most applications. Great for today's loud, high-performance engines, or any straight through transom exhaust when idling or cruising. Parts included in kit: (1) pair 4 1/2" stainless steel exhaust tips, (2) actuator solenoids, (1) relay solenoid, (1) pair 4 1/2" stainless outer transom rings, (1) hardware kit, (1) pair inner flappers, (1) pair outer exhaust lappers, and instructions. May be used on stock 7.4 MerCruiser up to most modified blower motors when running wet exhausts systems. Since all AT-450's are manufactured in house, we'll guarantee all workmanship for one year and electical for 90 days. In stock now! Also available for new HP500EFI.

*Great Time to Install New Exhaust Hose & Clamps

Part Number:

TCM ST450SS 4 1/2" Exhaust System, No Inner Flapper Assembly
TCM ST450SSFP 4 1/2" Exhaust System, With Inner Flapper Assembly
TCM ST450SSHPEFI 4 1/2" Exhaust System EFI
TCM ST450SSHPU EFI Exhaust Tip Upside-down