I went through the same decision process last year. My choices were the 33 or 35 Fountain or the 32 Sunsation. I went with the 496 due to cost and turn key reliability. Mine have been great so far!

496s' for sure. Hav an aquaintance that runs the snot out of his at WOT everywhere and if they can last under that idiots throttle hand they are just about bullet proof. There will always b someone faster and like Paradox stated if you want more power have something less complex built than the 525. I guess it depends, as always, how much you got and how much you want to spend

Had the 496 in my Nordic for three years, started every time (that alone is priceless), ran great, little maintenance. Doesn't have the bling & bark of the 525 but the price difference was too much for us at the time. Those CMI issues with the 525 have stung a few that I know.

525. They have turn key reliability too.That's what you are paying so much money for. A head rebuild after 250 hours or so is not that big a deal. It's probably due to the fact that the 525 has the most radical cam of all the Merc Racing engines since it is the only N/A one. It's also why it sounds so good . BTW, putting manifolds on a 525 would ruin it as it needs long tube headers to scavange exhaust and make it breathe.

I've owned a 496 and now own a 525. Both are great motors. The only downside of the 525 I see is the price.

Lots of posts in the tech section about alarms on both motors. If you are going to own either motor, do yourself a favor and buy a scan tool or diag software. Most of the issues are easy to diagnose and fix. Also, I think smartcraft is pretty good. I have it on my 525, didn't have it on the 496.

What is the average cost to service the 525 heads (at 250 hrs) and does the engine need to be pulled for this? I would think the staggered configuration in the 2007+ 35 Lightnings might make it easier to work on.

It isn't all that cheap to do the 500 or 525 top end. The parts are expensive. Start looking up just the parts and you'll get a good idea. Springs, cam, etc.

"reliable" is a relative term. The 496 should be a reliable 800+ hour engine. The 525 will need the BS done. basically, if you want to go faster you gotta pay.

I have the 496 mag in my 2005 25 Outlaw. 250 hours so far without one issue with the engine. Starts every time and has never left me a day without boating. I have owned it since new.

Twin 525's in the '05 42. One header leaked at 109 hrs without engine damage. Sent it back to CMI who fixed and pressure tested it free. No problems since. Change oil every 25 hours. Keep engines sprayed down with Corrosion X (red can). I have had absolutely trouble free turn key operation to 309 hrs. Not one cent spent on repairs (other than the header).

Whats the header issue on the 525? At the gasket? Im looking at a pair of 2007's with 96 hours on them......I want to move up from 496HO to 525, but all this reading is making me nervous.....