I remember reading on several threads on OSO about people swapping out older power for Merc 496's and I questioned them about the exhaust locations. They said that the locations were the same. I'm not sure what what the minimum center requirment is. I highly doubt that Fountain was cutting transoms any differently for 496's and 525's though. I would call Shogren. I'm sure they would know 100% for sure. Here's an ad for a 496 35' http://www.seriousoffshore.com/classifieds/index.php?page=out&id=478