A few things you should take to mind....1.Power
Since your wanting more power it seems that you got the bug... And this is prob just the beginning.. So with that being said instead of doing a small jump in power I would go with a big jump. This way it will keep you happy for longer and your not upgrading the motor ever few months and spending a lot of unnecessary money. I started with a stock bolt on banshee. Then went to a 4 mil ported setup. It was a good jump at first but I grew out of the power quick and wanted more and ending up again going with a bigger engine.
I think you would really like a 10 mil serval on pump gas. It will have tons of bottom end, be cost effective with pump gas and still put out close to 100hp with the correct pipes and supporting mods without any porting... Which you can port later if need be.
2. Suspension
While a bigger more powerful engine may fulfill your thirst, to be faster you will want a good suspension setup to soak up all the bumps and not be bouncing around on those pogo stick stock shocks that come with the banshee. Suspension upgrade will make you faster regardless of which motor you build/have. I got the power first then did the suspension. Some may argue that you should do suspenion first but as long as you do both your be able to really enjoy your bike.
3. Gas consumption.
While you make more power with a bigger engine and bigger carbs your bike will burn more fuel faster. This is something to take into consideration especially if you take long trips out when riding. Its a trade off that you get with more power. However there is things such as oversized gas tanks to fill the void and have more time on a tank.
4. Bling vs performance
I love me some chrome don't get me wrong. If you look at my bike it's pretty obvious. I would get your chrome covers Ect later after your setup/motor is good and where you want it to be. Think of it this way.. It would be like putting the finishing touches on your masterpiece.
5. Prices and $
A proper bigger motor setup is going to cost some good amont of coin especially with some good suspension. But once you have it all you can sell some of your old stuff like pipes, cylinders, crank, carbs Ect to help refund some of your money.
Wow that was a long post I think I just pulled a windy