Just bought and about to install a Cobra 75wxst. I plan to run and external speaker in the sound bar padding above my head. I picked it as my jeep is my DD and I liked the fact it was totally out of the way unless I needed it.
As Eddie said I read a lot on issues with volume. Most reviews said it was marginal for the hand set and ok with external speaker. Only time will tell once I have it hooked up.
Regarding volume, I should clarify that most of my grievance about the 75 was at high speed running a soft top or in general while running topless and doorless. Under those conditions, I could barely make out what was being said.