I spoke with Ian at Ilmor today on other matters, and this came up. "No plans for more power in the near future." Oh, well...

If you were to take a guess, what would he do, supercharger or turbos?

It's my understanding that the V10 is hard to get reliable results from at sustained high hp levels (900+). (I emphasis sustained, as there seem to be lots of builders who get big numbers in drag and road racing configurations, but that is entirely different.)
That being said, it would make sense to go with a screw-type/Whipple supercharger instead of going through the expense to engineer a marine-rated turbo system. It's such a limited market when you get into the really high hp levels, it's hard to get development costs back with small production runs. Given emission regulations, I don't know if a turbo package would be better or not...

Chief, Sterling and Merc have developed twin turbo systems. I don't see why Ilmor can't do it.

I still say they are working on a bb v8 engine.. these guys are pretty smart, and know it would be a smart move to compete with mercury.

Ilmor is defined by the V10. If they can get 725hp out of a 505ci n/a engine they should be able to get over 900hp out of a 700+ci V10 motor.

But you could be right CR, time will tell. Whatever direction Ilmor decides to go in though, V8 or V10, they will succeed.

Knowing the ridiculous 2000+ HP numbers you see out of Vipers for racing applications, I find it surprising 900 is difficult for a marine application.

Could they be waiting on the new viper v10 engine to debut in the 2013 viper?

I know a v8 700+ ci motor is expensive by itself. Wonder what the price tag would be on a 700+ ci v10?! Just about everything will need to be custom, and nothing off the shelf, other than maybe pistons, rods and bearings ect. Like a 4.5x4.5 or 4.6x4.5 bore/stroke deal. 747 ci has a nice ring to it

The v10's that pushes 2000 hp is running race fuel, and are mostly used for the strip. Not exactly a daily driver. Heck, several good builders are pushing 2500-2600 hp on 454 small blocks, just look at what Tom Nelson is doing. Car and boat engines are completely different. 725 hp from a n/a 511 cid OHV motor, on 91 is no small feat.

Now, a DOHC v10 would be interesting.