> "I've read most of the posts about the Q-filter and I think I will try it."

It's not applicable to all pups and configurations. It works especially well with the L-500XL (and also the L). It also works well with L-280s and L-290s. But, eg, in a guitar with an L-500 lead and L-280s/L-290s, IMO you would need independent Q-Filters, or just a Q-Filter on the L-500.