Someone's watching you closely--I'd guess the neighborhood is pretty stable, older and established, so two years later you're likely still the 'new kid down the street', and someone is trying to be proactive and keep the decibels 'like they always were'. There may be a shift worker within earshot that does nights... may be some history of excessive noise and poor relations in the area someone's trying to nip in the bud, may be a young family with kids in bed by 7 or 8 that woke up crying, or even a migraine sufferer...
Eric's idea of getting to know your neighbors is a good one, and a tremendous outward gesture of good will whether people attend or not. Hand delivering invitations with some fresh produce, and mentioning--in passing--remorse about the noise complaint, the ongoing LEO problems, and how you wish you hadn't lit up the tires and started the cycle would likely break it. A lot of effort to do so, but worth it if it troubles you, and you change from the stranger down the street with the loud truck to the nice young man that brought produce and extended a courtesy. It may be the LEO is from the neighborhood or has a relative nearby--or very little to keep busy.
Then there's the truck--is it too loud? There are people that love to hear loud noises. I hate noise, from barking dogs, to loud bass, to spinning tires, and the motorcycles designed to make tons of noise--I don't get that anymore than them hooking up a 100db stereo to try and hear over their own noise, but to each their own. I make excessive diesel, equipment, and tool noise sporadically, but try not to fire anything up before 7am, and have everything quiet by 7pm.
Different strokes for different folks usually has the credo: so long as it doesn't harm me or people I love.
