After Reading some postes on Jetting I contacted FMF and asked them the Following

"I have an 87 banchee that is bored 60 over with a set of FMF Fatty series pipes with Power CoreII silescers. I Am running at about 1400 Ft and have the air box intact What is the Proper Jetting?"

And the answer that I recieved was

"Run 160's Mains and 30 minors with the snorkel Removed"

From Readin other posts this semaes Lean

What do you think

 

They probably meant 260 mains......I'm running fmf's with the stock filter and lid, it's a little rich with 260's so with the lid off it should be just about right. I'm at 2,000', pretty close to your level...

 

With my 99 BANSHEE I run with out the airbox lid and have a K&N on a prodesign adapter. I have 300 main jets, new needles and 30 pilot jets. With the air box lid on 260 main jets and the stock 28 pilot jets should be fine.

 

Thanks for the Info I will be trying it this weekend and will post my results