i have compared the std schumacher 'o' rings and the nortech versions. there is a huge difference in the amount of 'stiction' - the nortech ones are so much smoother and leak a lot less.
there is one thing that i have noticed - i have run my CAT for only 6x 5 min runs and the supposed 'nitride' coating is already wearing off the shock shafts
. my S2 has run for the same amount of time on the same track (coventry astro) with new losi shocks and shows no wear whatsoever. i have to say, the overall quality of the schuey shocks is pretty poor in comparision. the shock bodies are poorly finished internally (plating burn marks on the bore and pretty rough surface finish), the seal retaining caps are waaayyyy too thin on wall thickness (why aren't they the same o/d as the shock bodies to give them some strength ? - i've stripped one already before it was finger tight). its a shame really - i'm thinking of going over to losi shocks on the CAT because of the quality issues.