Robart air restrictors on Centurty Jet retracts?
 

I have a set of Century Jet retracts on my P-40 that I want to slow down before they destroy themselves. Century Jet specifically said not to use Robart restrictors on their gear, but I assumed that was because they wanted to sell their more expensive adjustable air valve. Before I cut my air lines, can anyone confirm success or failure with doing this?

I can't see how it would make any difference what air restrictors one used. Long ago we would use wheel collars and tighten the grub screws to restrict the air.
I would guess your assumption was correct.

They work perfectly. They're probably half the speed of what they were before.