screw it to the floor, it doesnt cause any problems at all. I wanted to fasten mine down myself but the audio place told me that if they dont screw it down the warranty is voided as it is much more likely that u will go over a bump and the amp will flex and screw up the insides. if u screw the amp to the floor, have the wires facing forwards, as there is a nice little lip thing there that stops the front passenger kicking his legs back.