Always measure in 3 ft incrmts, thats what i was told 20 yrs ago. But ive tryied different lengths before and it didnt do anything different. I think you're reading into it too much. As for your mobile whip, it will never perform like an Antron, bottom line, i think we all know that. Matter of fact its the best bang for the buck. The other two i stated might be overkill for many ppl cause A) You're probably never gonna own or run 2,000 watts.....EVER!! B) Maco 5000 5/8 ground plane is way too pricey and just doesnt perform magic like some ppl have said. If you get a A-99 for $50 bucks, you already have one of the best. After that put your $$ in another area of our hobby, radio upgrade, bigger linear, bigger P.S. etc. Just dont throw money at bad ideas, take it down over & over, just trying to help.