i say get the registration and inspection cleared up, and then call his ass on it.
tell him to call the cops, and that you'll wait for them.
most of the time if you call their bluffs, they will just stfu and back down.
i went through the whole spectrum of BS noise complaints not only with the stang but with just random noise when i was living in an apartment complex.
i knew my stang was loud and just about everybody just let me be, and i did the same. i would tolerate other people, like if i had to work the whole weekend and next door had friends over making noise till 1 or 2 i didn't call the cops or even knock on the door to complain. I just dealt with it. just like when i was still driving the stang daily and in the winter i would have to leave at like 4:30 or 5 and that pig would be so loud in the morning, but no one complained. until this one snotty ****** moved in, let just say, she tried to make it hard for me and my family. but ending up with no power on nights it would rain or snow. and her locks would be glued shut when she went food shopping, it suxs when you carry bags of food up 3 storys to not be able to open you door.
sometimes you have to become a bigger ******* then them, and it will put them in their place. it's always worked for me. it's starting again in the townhouse complex i live in now everyone who lived there before i moved in 2 half years ago never had a problem with me and vise versa. a new couple moved in when the summer time started. and right off the bat i could see they had a problem with me and my wife. it starts off with the dirty looks and then the complaints start coming in. the onsite manager i could see started to get worry, like he thought i was becoming a problem. and by the fourth complaint he realized they are the problem. the manager will come to you if a complaint is made and ask your side of the story, he's very fair. if your not home then he slips a note under you door to talk to him about the issues. if you don't he thens leave messages on you answering machine. well on the fourth complaint he left a note, multiple messages and when he saw me i could tell he was a little pissed. but what he didn't know was i just got back form the airport and was a way for 2 weeks on vacation when the dips ****s made the complaint. so these nimb rods made a false complaint while no was home. lol i even gave him a copy of my ticket stub so he could file it with the ciomplaint the was made 3 days after i left . lol now he realizes why the first three complaints i would tell him i have no idea what your talking about, he thought i was been a dick about it. but they were all made up. time to start collecting on payback.
btw i just notice i hijacked your thread. sorry man.