Can't help a lot with how to set up a 353, but I have run Hydros a lot over the years and your description sounds typical. Are your Hydros the P5's or the P5X's?

On the shifting issue, Bravos are a cone clutch drive and as such need to be in gear or in neutral. Anything in between will cause the gear chatter you describe. Try to be a little more intentional in your shifting, simply put just shift it in or out. Going too slow will make it chatter.

The 525's are a tad rich from Merc as are most of their motors. One thing that I have started doing with mine is to simply start them up, no throttle advance at all, and let them warm up at idle. I let them sit and run until the temp is up to normal and the oil temp gauge begins to come up. When I first got this boat I did the same thing I had always done on my carb motors, start them up, then jack them up to 1500 or so to warm up. The 525's just don't seem to like this, seems that if you mess with the throttle position before they are warmed up it throws off the computer program and they load up, and it shows on the transom more so. You will always see some soot there, but I did notice it seems to be less since I started letting them just fully warm themselves up on their own. I guess the computer is smarter than I am.

Soot is generally caused by premium gas. On 525's use regular only. They run better and no soot..really no bs!. When getting on plane use some down tab. Sometimes you need to rock the wheel back & forth to break loose the props. You can also trim the drives out a bit until the props break loose then trim in to bite. Or put in 700 NXT's..she launches out

I just made my first run of the year last Sat, and I also had a lot of soot from my 500's. The cold early spring water causes it in mine and later in the year it go's away. Pain in the ash to clean though, no pun intended.

Washes right off with a little Zing on a cotton toilet bowl brush. Takes just a couple minutes then a quick rinse with water. Hardest thing to find is the old style cotton toilet bowl brushes. Only place I ever find them is at the Ozark Barbecue store down at LOTO. Exhaust tips come out looking brand new too.

Any of you guys know history of 2007 Formula 353 Mahopac Marine has for sale

Don't know the boat, but the Guys there are real friendly! Looks like a pretty good deal. With 300 hours, I'd see what the computer says how those 525's were run! A survey should be on the list too.

Dave

you should check with a mercruiser dealer about the soot on the transom it should not be bad at all the engines may fall under a re-cal according to the serial #'s a good dealer will be able to tell you that or p.m. me your serial#'s and i will call mercruiser for you. a service rep can reflash the ecm's on the engine at your dealers shop. just had one done for a friend of mine last summer cleaned his transom right up.

Thanks for the info Past Due, I will check that out when I get to the Ozarks this month.