I have a 99 Banshee with FMF Fatty's, Power Core 2 silencers, and a K&N filter with holes drilled on the top of the airbox lid. It seems to be bogged down from 1-3 gear. I currently run 260 mains and 25 pilots...I was wondering what size of mains and pilots I should be running...I live in Texas at low altitude and the heat here is horrible.

99 Banshee FMF Fatty's, Power Core II, K&N filter

You should use 30 Pilot jets and adjust the air screws. You might want to richen up the mains as well.

what size mains would you suggest?

Mains I would try a 280-310 depending on alt. and temp. You always want to be a little on the rich side.

I am running 30 pilots and 295 mains. LRD sent me the 295 but I am going to put the 300's back in. mine is overheating way bad, and I think the 295's are just way to lean. I am in Texas to, but I have a 370 kit using VP-C12 at 100%, so you may not want the 300's. You could maybe go with 290's or 295's. Just try both and see what happens. If I am right you do a lot of MX racing. If I am also right you are racing in Texas. I would loose the K&N and get a dual foam. It is just to dust down here for the K&N's. When CT tore my motor down for the 370 kit he called and ask if I was using a K&N. I told him I was and he said it was easy to tell. My crank bearings were full of dirt. I would like to say it was because I was to lazy to clean filters and pre-filters, but that wasnt the case. I cleaned my filters after every ride or race. And for the dusty tracks I had 2, so I could swap between motos. You might loose a few ponies, but engine work will cost you more than a couple of horsepower. Good Luck with the jetting!! I have always had trouble jetting. Luckily my motor builder has hung in Texas before and knows our weather and sea level height down here. He also knows how dusty it gets!!!!
LATER

I don't race yet but will be next year...Where do you race at? Where is the best track around this area that will let you practice? what type of filter set up do you prefer. Do you know where I can get a good set of nerf bars fairly cheap?

99 Banshee, FMF Fatty's, Power Core II, K&N

The only track I know of that is close to you that will let quads practice is the TEXOMA track in Greenville (caddo). I have a PRO-DESIGN pro flow filter and intake plate. It is a really good filter. As for as nerf bars, I would say give K&K atv a call. When everyone is out of things, they seem to have it. They may even have some used ones for you CHEAP!!! LATER

I'm running Toomey pipes and 2:1 uni filter, my dealer put 310's in, runs great!