I posted one earlier about my middle pickup sounding thin after the star grounding technique. No help from you all, but I did solve my problem - FYI, I cut out the isolation capacitor that is recommended and that solved it. Don't know exactly why, but I noticed when I plucked a string using only the middle pickup, the tone would start out full and quickly turn thin-sounding. Sounded like a CR circuit phenomenon to me. Now that I look at the mod, I'm wondering what that cap can do anyway. It is wired between the pot shaft, which is grounded to the foil-covered pickguard, and the other end of the cap is wired to the star ground, which is connected to the foil of the shielded cavity. The pickguard is also connected to the shielding foil of the cavity. There fore, the capacitor is connected between common ground. It won't do much good like that, unless I'm missing something from the instructions. It does say the foil on the pickguard should contact the shielding foil of the body cavity.
Sorry you didn't get a reply. I don't recall the post. Anyway, it sounds like you have it wired wrong. The star ground is where all the ground connections from the pickups, pots, etc. join, it just floats there connected to only one leg of the cap. One end of the cap is then connected to the shaft of one of the pots which in turn is connected to the foil shielding. Double check you star ground. It should not be connected to the foil directly unless you are not using the capacitor. The pickguard and cavity shielding should touch.