so ive been running a mag mount for about two years now on my truck, just a basic dual band whip, works ok but i keep reading that a proper NMO through-the-roof mount is way better and i'm starting to believe it after messing around with the numbers a bit. the mag mount sits on the roof towards the back and honestly the swr is fine, like 1.3 or so on 2m and a bit worse on 70cm but nothing alarming. but i notice when im driving through hilly terrain i get a lot of dropouts talking to the local 147 repeater and i'm wondering if a solid ground plane from a real NMO would actually make a difference or if my dropouts are just terrain and i need to accept that.

truck is a 2019 F-150 and yes i know drilling feels scary but ive done it on older vehicles before. the other option i was looking at was one of those lip mounts or a hatch mount but i heard those can mess with your ground plane even more than a mag mount. anyone actually done a side by side comparison? also debating between a larsen nmo150/450 and just going with a diamond mr77 or something. not sure if the antenna choice matters as much as the mount at this point.

honestly the NMO through hole is night and day vs mag mount and ive done both on multiple vehicles. the mag mount ground plane is only as good as the contact patch under the magnet and on modern vehicles with thick clearcoat it's often not as solid as you'd think even if the swr looks ok. swr can look fine and you're still losing signal to a mediocre ground connection.

that said, your dropouts on hilly terrain are almost certainly just terrain. no amount of antenna improvement is going to let you hit a repeater that has a hill between you and it, that's just physics. what a better mount might get you is slightly better performance at the edge of coverage, like when you're just barely in range it might stay quieter a bit longer. the larsen is a solid choice, ive used the nmo150/450 for years. the diamond is fine too but the larsen feels more robust physically, the whip is stiffer. either way get the NMO installed properly and you'll feel better about it even if the practical difference on that repeater is modest.

lip mounts are kinda underrated imo, i have one on my jeep on the rear hatch lip and swr is pretty comparable to a trunk lid NMO i had on my old car. the ground plane thing is a concern but in practice it seems fine at VHF. wouldnt trust it for HF mobile obviously but for 2m and 70cm it really hasnt been a problem. saves you from drilling which on a newer truck i get the hesitation.