It made some weird sounds at idle when I first got it, but it has gotten better. I guess that it had to break in, because I believe that the squeal came from my belt. It was probably due to the pulley on the mean green being smaller. I think that the belt just had to adjust. I can get some dimming out of my setup at full volume , but I don't think that's because of the alt though. My US Amp draws a whole lot of current compared to the KX850.2 that I used to run. The US is rated for a few hundred more watts, but it seems to be a lot more inefficient than the Kicker was.