The huge stainless whip may give you the best transmission and receive, but why do you really need that when you're just trying to talk with the group your riding with in the trail run.
I personally find them annoying, had one in the past, pulled it off shortly after installing.
Went with a shorter stainless whip with a base coil, works perfectly fine, even used it in the rig when I drove OTR.
Now I just use a magnet mount K-40 on the roof, works awesome, gets out great, especially with it mostly in the center of the roof.