most banshees have a light switch powerband. they will be kinda sluggish on the bottom end, and then once about 6000 rpm hits, they start running like a bat out of hell..
this can be cured with porting geared towards more the bottom end. pipes, reeds, and different sized domes can also affect this.
basically, without spending some money on your bike, youre stuck with the type of power it makes.