Okay so I installed a single 12in subwoofer a while back, nothing special, it's a pioneer TS WX1210A with a built in amp. It's at least twice as loud when the car is not moving. Does not matter if the car is running at idle or off it's still way louder when stationary. I have tried revving the engine in neutral when stopped it still stays loud. I can pull up to a stop light and the thing shakes the car, start moving again and suddenly it's nowhere near where it was. I have a 90amp alternator, the lights do not dim when the bass hits. Battery is a Napa legend, nothing special. Sub is inside the cabin of the car in the back seat, it's a Honda prelude so pretty small cabin. I thought it could be some weird issue with the battery or alternator but if so wouldn't it be louder or quieter when the car is off? Anyway any thoughts would be appreciated.