Hello folks I'm new to this site!

i have a few questions right of the bat.
I have a 05gs500f and i wa't to get it after market upgrades, K&N filters rejetting and exhaust I just got a used yoshimira slip on and wanted to get feedback on the what next. What jet size should i go to? where can i get a flange mountiing to install the slip on ussing its bolts? What other modds are reccommended? GStwin.com was of little help.

-Remy