In reply to Matt Buchanan: Same set up here. I seem to remember concluding that the Ultra had the same mid sole as the Manta Pro which was different from the Phantom Guide. I had to stop using Grivel G20 as I found the set up too flexible. I think if you get a resole and go for the Phantom Guide/Mont Blanc/MB Pro sole and mid sole that should stiffen them up. Just the sole will probably only help for the first time you use them. I wonder if you could get a Rebel Ultra mid sole?