Vladimir- The upgrades are sort of a homegrown tweak. I have worked with highly regarded audio guru's(most in the biz) paired with a little common sense and a LOT of experimenting. What Gladstone and I have done is some what involved, first you MUST bypass the fuse and midrange fuses and attenuators and all of magnepans factory connection(except where they go into the drivers themselves) for that matter. An all external passive crossover network, made with high end components, internally rewire the speaker(though not the panel itself) and then get some form of stand that does more then just hold the speakers up. I have also removed the internal grill from the front of the speaker, it still has the external grill that you see with the fancy trim. You must be even some what technically capable and willing to perform surgery on your speakers, no company makes full hot rod conversions for magnepans. I was thinking of doing it, but not only is there not much money in doing it, I think its fun to have a real knowledge of what's really going on in your speakers. Even if someone made a kit that they could ship you, you'd still need to "gut" the speaker yourself. I know cardas makes some sort of wiring kit, but there is no way its an internal rewiring of the speaker. If you have any specefic question contact me privately and I can give you all the information/experiences I have gathered.
