[BLouIsGod]

The amp shouldnt affect the alarm at all. If your tapping on the fuse box and it fixes the alarm, there just a lose / crossed wire or a bad relay there if the alarm has one. The sub has probably created those rattles though. A big spot for rattles is the rear deck lid and the rear window - if they can fix it, get some weatherstripping and wedge it way down between the lid and the window.