When using the quaco kit, the wiring "route" is a must because the way the new boards get wired to the chassis is different and the old wiring wont reach, gets bypassed etc. Plus....the old wiring is very stiff, hard to work with. The wire that comes in the kit is soft and flexible. The stiff wire can lead to side loading the components that it is soldered to. Aaaaand, it is a heavier gauge and in theory, better. I upgraded the chassis wiring more out of necesity from the kit than because i can hear the new wiring.