It is possible.Porting will make a huge difference.I'm sick of hearing about banshees that can do over a 100mph.Alot of them can but come on.It takes more than just pipes.Keep in mind too.Even if you can hit 90,who cares if it takes you forever to get there.
I had some guys ask me how fast mine should go.I told them around 90-95.They was shocked.They told me about this banshee that could do 112.Maybe he could,but I beat I'd smoke him in the 1/8th no problem.Just my opinion.
Get a good port job,good set of pipes(CPI/shearer),larger carbs,different head,and weld up the crank and that banshee will be quite a hand full.
My friend Michael has a dune ported(F.A.S.T.).Even with stock carbs,that banshee is extremely strong.I'm impressed.
He runs holeshots.Right now his gearing is 13/41.We know he should gear up to either 14/41 or 15/41.With the 13/41,it spins something fierce on asphault with his' holeshots in 1st and 2nd.In 3rd,it will lay down about a 10 ft. black mark.Remember,that's with stock carbs.Jeff is awesome on his' porting.