The new Mercury V8 outboards sound pretty good especially the 300R and 450R. With that being said, the new Formula 1 racing engine, the 360 APX, based off of the 300R, sounds even better because of its above water exhaust. The consumer V8's have a "sport" mode which makes then slightly louder and deeper at idle and low speeds but has little inpact when running faster. The sport mode lets a small portion of the exhaust come out the back of the outboard, pictured here, while the majority continue out the prop.

The new 360 APX has all of the exhaust coming out just above the prop at the bottom of the midsection.


Has anyone done or looked to do an above water exhaust on the 300R or 450R and is there any interest in a system that would allow for this? The best way I can think of doing it is to keep the standard exhaust going out of the prop but then the sport mode would close a larger valve dumping all of the exhaust out of the back, above water, thus giving a much better sound when running. This would allow for the motor to stay quiet while around docks or for cruising but can then be opened up when is necessary. To make this work I would image only 2 or 3 things would have to be changed on the motor. A larger valve and exhaust would need to be installed midway through the exhaust system and a larger hole would have to be made in the cowling, where the current sport mode hole is, to allow for a larger pipe to exit the cowling.
There aren't many videos of the 360 APX running but from what there is it sounds pretty good, intrigued to know if anyone has made theirs sound similar or if people would want the option to do so.

ANY permanent modification to the cowling will void the warranty. That is why the aftermarket intakes use double sided tape to secure them to the cowling. At $18,000 per motor for the 8 year extended warranty I doubt anyone is willing to risk losing it for exhaust modifications.

Crazy....those intakes are a clear upgrade, not only to performance but an upgrade to the longevity of the engines....Merc should be paying to put those on

What intakes? Link?

Can you share a picture or link to these intakes? I can’t seem to find any.

MTI provides them for their customers. It is my understanding they do not make them available for non customers

Troy at Supreme Marine in Ft. Lauderdale makes intakes.

What kind of performance gain are people seeing with the larger intakes? They look like they would be very easy to reproduce a similar intake system on our own.

Correct. Helps the 450's breathe as at higher speeds the exhaust was creeping into the intake. I'm not sure on the speed increases seen. Rumors of 5-8mph...maybe more.