so ive been running a lip mount on my truck for about two years with a Comet SBB-5 and honestly it works fine but i keep reading that NMO through-the-roof is the way to go for a proper ground plane. my truck is a 2019 F-150 and im a little nervous about drilling through the roof just to chase maybe a couple dB improvement. like is it actually noticeable in day to day use or is this one of those things that only shows up on a spectrum analyzer and not in the real world.

for context im mostly doing local repeater stuff and some simplex on 2m and 70cm, nothing crazy like weak signal work or contesting. range out to maybe 30-40 miles is plenty for what i need. the lip mount does have that slight angle issue on my truck because the cab lip isnt totally flat so the antenna isnt perfectly vertical, probably off by 5 degrees or so. not sure if thats a big deal or not.

anyone actually done both and can compare? or is this a situation where if it aint broke dont fix it

honestly for repeater work you probably wont notice much difference and id leave it alone. the 5 degree tilt is basically nothing. where NMO really shines is the connection reliability over time - lip mounts can work loose, get moisture in the coax fold, all that stuff. ive had two lip mounts fail on me over the years, one slowly degraded over about 6 months and i couldnt figure out why my audio kept getting reports of being scratchy, turned out the connector was corroding inside the mount where i couldnt see it. drilled the roof on my last vehicle and never looked back, but i get it if you dont want to put a hole in a newer truck.

if you do drill, get a good NMO mount with a rubber grommet and seal it properly with self-amalgamating tape and you'll never think about it again. the Larsen or Diamond NMO mounts are solid. just dont cheap out on the mount itself.

i went through this exact thing last year, different truck but same dilemma. ended up doing the NMO drill just because i found a good deal on a Diamond NR770HB and it felt wrong to put a nice antenna on a sketchy mount lol. honestly the difference on 70cm felt noticeable to me but i cant say if thats placebo or real. 2m seemed about the same. the install was less scary than i thought, just go slow with the step bit and you're fine. tape off the paint first.