i have a mag mount5000 coming off a Phillipine 148GTL running barefoot mounted dead center of the roof on my Jeep G.Cherokee Ltd. right now and i get a good tune through all 40 and up to 60 or 70 but once i get up to 80 or 90 to 100 it jumps up in the 1.4 range but i don't ever transmit outside of the normal 40 since there really aren't that many people in my area that are still on CB anymore.the ones that are on,stay within ssb and am.