hmph... I was reading a document that said :
Air filter
Remove snorkel:1-2 sizes larger on the mains, adjust airscrews
Remove airbox lid:1-2 sizes larger on the mains, adjust airscrews
Add foam air filter:0-2 sizes larger on the mains, adjust airscrews
Add K&N air filter:4-6 sizes larger on the mains, adjust airscrews, add one size on pilots if necessary
Add 2 into 1 Foam air filter OR dual carb-mounted foam filters (removing entire airbox, NOT in addition to removing snorkel and airbox lid above):2-4 sizes larger on mains, adjust airscrews, add one size on pilots if necessary
Add Dual K&N carb-mounted air filters (no airbox, NOT in addition to removing snorkel and airbox lid above):4-7 sizes larger on the mains, adjust airscrews, add one size on pilots if necessary
Add Outerwear:no change
Add TORS elimination kit:no change
.... So maybe 280 is correct. This will be the first time i have ever jetted so it may take me some time to figure out if its correct or not.