Hi Flo!
I have a buddy who has a pair of MG3.6R's. He has custom external crossovers. They walk all over the original ones in the small boxes. His custom ones are housed in black plexiglas boxes as large as a power amp. They are as heavy as a lot of receivers. The stock crossovers in Magnepan products while OK are not nearly as good as a replacement. Anyone that owns Maggy's should look into replacing the stock crossovers with new parts. It is not necessary to change any of the values. Just get better parts. The difference will amaze any Maggy owner. The difference in sound is such that you would think you bought a better more expensive pair of Maggy's.