The thing about 10in tires, is that it takes more RPMs to be at the same speed of a 12in. Plus, they ride rougher.
I enjoyed my 2k Clutch Springs on my 80cc 2t.
I have not had a problem, on 7 scoots, with unrestricting my Ex.
On my Falcon 150, I opened the Ex. case, cut the baffles out, but left the Fiberglass and steel screen, and cut .25 of the pipe off the end. bolted it back together and it runs better. Wonderfully better, with more top speed. Plus, being shortened, it looks better too. lol
That's a good looking BBK, and the price is nice, as well.
Hope you get it soon.