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...
I've recently installed 4 40mm sorbothane isolatiion feet under the existing adjustable 40mm feet on my Music Hall mmf-5 turntable. There's no perceptible sonic improvement as far as my ears can tell, but my suspended floor is pretty bouncy so I'm hoping they help, although I expect nothing can solve that problem short of a new floor consisting of concrete slab.
I use the Navcon silencers in my HW-19 and they work better than the sorbothane ones I used before that.  They have an aluminum base threaded for the same thread that held the springs.  I used some short threaded studs to mount them into the frame and could easily adjust height.  They also don't ooze goop and distort like the sorbothane did.  Unfortunately, I think they are no longer available.  I have occasionally searched for some more but no love.  Herbies may be your best bet.