Navacon or Sorbothane Isolators for VPI mk4

I have heard that the sound of the VPI mk4 TT will be improved by replacing the springs with Sorbothane isolators or Navcon Silencers. Can anyone tell me if they have tried this and what your results were?
Tom I know that I've read forum postings regarding someone's successful experiments with alternatives to the spring suspension, but it's not going to be especially easy locating those posts. I don't recall what was used (perhaps Black Diamond cones?) but the best result for each unique installation can vary widely, depending upon your own rack, shelf, flooring, etc. I'm also interested in others' techniques since I too have a MKIV.
Get some Herbie's Big Foot Dampers. Place the spring "bottom" in the hole. Herbie's on top and then the spring "tops" on top of them. I hope your tops have the three half-submerged balls in them.

I had been using the Navcom which Mike at VPI said was better than their sorbothane. This set-up is a substantial improvement over the Navcom.

System can be see at AA
I just ordered sorbathane pucks for for my MK4 to try instead of the springs I've been using for 10 years. No matter what i did my woofers would jump no matter how softly I walked by my table. And this is with A Big Rock 19, floor jacks under the stand in the basement, reeplacing the sorbathane feet with brass spikes and puting BDR pucks under them. The only thing I haven't tried is an Bright Star Air Mass 19 for almost $600. A little out of my price range. But I heard going back to the pucks helps. We'll see...