I'm changing out my wifes old Sportster with a Sportster 5. The old one was hard wired in by the installers at Best Buy. I think they tapped into the cig. lighter wire for power. Well, the tip (power) that connects into the base from the older install is larger than recepticle of the newer one. Instead of resplicing into lighter power again, can I just cut the larger older tip off and splice the smaller newer one on the existing install?