Ugh. 150 HP? Really?
If they had asked, update the 990 with lighter SOHC heads based on the new EXC/SXF, drop 50 or 75 lbs and 95 HP is already more than enough. An easier to access air filter/heads/oil changes, a single fuel tank that maybe extended under the seat/subframe to make it thinner up front. After a decade the engine could have been cast cases like the new dirtbikes too, lighter, stronger.
If I wanted a BMW/Ducati/Triumph I'd just buy one.