Stretching to 159"
Yes, Increased flotation! I would extend the tunnel, you don't have to change the heat exchangers though.
Dave;
I had a 04' Summit"X" 800 144" that I extended to 159".
Change from the 10 tooth drivers to 9 tooth that can be bought from Ski-Doo for $50 a piece(need 2), then you can leave the stock gearing in the chaincase (19/45)depending where you ride, may need a 46 on bottom?
The sled I sold,
but I still have a 159"x16"x2.25"track 06'model(200miles) and complete skidframe (159") with Ice Age manufacturing billet rails(powder coated black) set up with 8" Bigwheels that are powder coated black also. Also have a Team secondary complete with springs and helixes for both the 144" & 159" set ups.
PM me if you have any questions?
or if you might be interested in any of the items I could send you some pictures.