Man, you don't even need that much. People over-rate the cost of performance parts for banshees. I always hear about how they cost so much more because you have to buy two of everything...blah, blah, blah. If that's the case, why is a new 4 stroke exhaust the same price as a banshee's exhaust? Piston kits are the same cost for a banshee as they are a yfz450, if not less. Cranks are the same price....
You could stroke, port, buy new carbs/filters, reeds, and a new head to bump up the compression for WELL under 3,000 dollars, and have a 90+ HP engine. You must not do the work yourself. You should really do some research before coming on here bad mouthing banshees like you know what you're talking about