If you can find one, Plowman mount to keep the engine in place.
Yes stock clutching is pretty darn good on the 08 but BMP torsional works just that much better.
Agree on studs, even heavily studded sled will drift the corners with ease, run down the center only.
Y pipe, works best with a fuel controller such as Boondocker, either way pipe means premium fuel only.
If it's a Sno Pro, dramatic improvement in ride ditching the air shocks for LXR version coil overs. Also good gains in ride quality having rears revalved.
Skis, after trying a bunch of em out there, settled on SLP / SLT for skis, also liked the Doo Pilot skis but lil too much push in loose snow. Loved the Simmons (tried both Gen I and Gen III but you do pay a penalty on effort to turn the skis on frozen hardpack.
Can't stress how much difference in clutch life you'll see keeping them blown clean between rides.
Be sure to remove the lower air box and add Gorilla tape to the outside where exposed.
While I really liked my 07 F1000, the 08 was a much better sled out of the box.