Where I am right now is plastacine lined baffle, removed white cloth with thick felt covering the driver and transpore at all four driver corners. My cups have a think layer of plastacine with paxmate over it. My bass ports are covered in electrical tape with 5 pin holes in each. Outside I have 840 pads with no other mods. I have been considering removing the external driver covering because I had been using felt under the pads with the stocks and the Shure pads have their own liner. With the 840 pads, I currently have about 3/8" of open celled foam under the rear of the pad to elevate it slightly.
Overall I am very happy with these. Before the mods I couldn't stand these compared to my highly modded Grado SR60s, but now I haven't listened to the Grados in a while. By far the biggest mod was removing the white driver cloth and finding a fairly heavy felt to cover it with. This dramatically increased the bass quantity and quality.
My only wish is that I could compare these to some other modded Fostexes to have a baseline. Although I am happy, I am still curious where these would stand compared to what others are listening too (or ideally a pair of LCD-2s).