so anyway after probably three weekends of messing around with this i finally got my FTM-400 installed in the truck the way i want it and figured id share what i ran into since i saw a few other threads asking similar stuff.

biggest thing was the power cable routing. i ran it directly to the battery like everyone says to do and that alone fixed the noise issues i was getting through the speaker when the engine was running. had it hooked to the fuse box under the dash before and man it was awful, could hear the alternator whine clear as day every time i revved it up. direct to battery with the 40amp fuse close to the terminal and all that went away.

the other thing that took me forever was the antenna. i went with a NMO mount through the roof which i was honestly terrified to do but its so much cleaner than the mag mount i was using before. signal reports are noticeably better and the mag mount was scratching the roof anyway so im glad i just committed and did it. used a Tram 1185 for now, might upgrade later but its doing fine for hitting the local repeaters.

control head is mounted up near the rearview with the RAM mount system. takes a little getting used to having the head separate from the main body but once you get used to it its really nice.

anyway if anyone is thinking about doing a similar install and has questions feel free to ask, still learning myself but i went through enough headaches that i might save someone some time.

the alternator whine thing trips up so many people, glad you figured that out. direct battery connection is almost always the answer and its one of those things thats hard to believe until you actually do it yourself.

one thing i'll add for anyone reading this later -- if you still get some noise after going direct to battery, a ferrite choke on the power leads right at the radio can help too. also worth checking your antenna coax shield is actually grounded well at the mount point. bad coax ground can cause some weird audio issues that feel electrical but arent coming from the power side at all.

nice choice on the NMO mount, mag mounts are fine for playing around but a properly grounded NMO through the roof is just in a different league. what repeaters are you hitting regularly?

this is super helpful im about to do basically the same thing in my jeep with a 578DGPS. been going back and forth on the antenna mount situation for weeks. did you have to do anything special sealing the NMO hole? thats the part im most nervous about, last thing i want is a leak showing up six months from now