I've seen a few of these on the fountains, they're straight pipes that are fastened under the swim platform and come back so that there flush with aft edge of platform. Has anyone seen these and know why they're used??

Had them on a 2004 Fountain 29' with a 500hp. They are mufflers. Sounded like crap. The boat had silent choice on it so why the mufflers to. I guess in some areas the water police will give you a ticket with straight exhaust. I took them off and put regular pipes with the flaps.

Thanks for the reply SF, was just wondering if they were added because tips are under water a lot of the time, reversion???

Nothing to do with reversion. They are long mufflers. I have seen them on quite a few 29's.