hello FITO

the engines that i have seen go 3-5 gallons were all on the orignal rods and piston and sleeve sets.

on those same engines we did replace the rear main bearings after about 2 gallons, but this because the acid in the nitro is very agressive on the metal and causes the balls to break down so to be safe we replaced them with a ceramic rear bearing.

the rods have been very good on the xenon series engines, as for what you gain or loose on the regular xenon versus the "R", the R since its an aluminum sleeve engine will be much more sensitive on the needle settings but the power of the R is much better all around.

if you are an experienced racer i would recommend the XenonR, if not i just suggest sticking with the regular xenon thats an ABC motor.

good luck and happy holidays

kevin @ RB USA