My tip is to reserve your fears until you get the car back. :-) Don't second guess yourself. When you get the car back be absolutely critical about every aspect of the install. Look for scratches and damage if any, listen to the sound, do a channel sweep (left right, front rear) make sure all th rca's are properly connected (common mistake and evidence of a hurried install). Check for clipping turn the volume up. Use the loudness control to exercise the sub, if you have the mlord kernel use the bass control to make sure the sub works as expected.

Is there an empeg in your nova?

Calvin