If you are talking about hi power systems and amps, make sure your old electrical system and alternator are up to handling the load (assuming you are talking musclecar era). If you burn something up, you'll be unhappy.

Scott B. "I'm a self-made man... I started with nothing, and I still have most of it!" 68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph 69 340 GTS stock 14.18@ 95.60 mph 01 5.9L Ram 1500 Quad Cab 4x4 01 3.5L 300M 16.23@ 86.97 mph