Such an odd recommendation from a master mechanic ? My pan has loads of after market goodies fitted...no problems in over six years with any of it. Smaller machine may well have limited options ,but anyone with electrickery expience should be able to work out if any bike would struggle to run something, problems usually are the result of a bad installation . Today's alarm and immobiliser systems fitted to vehicles often prove to be more of a barrier to fitting extra stuff rather than the stuff it's self. Often easier to dissuade the idea than go down that long and lonely road ;-)
