Monty,

Carbon is old-speak, most are going for Tracys' ceramic seals. The take a while to break in, but seem to last very well. Rotor housing wear hasn't been a problem for anyone not using a 100,000 mile motor to start with. Ed Anderson ran into some trouble with ROTOR tip seal slot wear, check yours carefully. I defer to Tracy, Ed and Lynn as to the corner seals, nobody I know has really worn out a motor. (including racers in sedan classes!)

Bill Jepson