Okay. I just installed the new Browning BR-92-BL antenna on my peterbilt truck. I had to mount it on the back of the cab on existing suport bar using a heavy duty mirror mount. I centered the antenna in the middle of the cab . I grounded the mount and antenna to the truck frame. The coil ended up being close to the roof of the cab. The antenna is 68" long .How does that affect the transmit of the radio? I ordered a 22" Shaft extension which would make the antenna 90" raising the coil above the cab instead of 68" stock length. How would this affect the transmit and swr ? Would you recommend this conversion? I can pos a pic if helpful