hello, can anyone advise, i bought my nsr a few months back, she's only being used for the odd track day at the mo, Andy did the crank around 3000kms (20,000kms on the clock at the time) ago and i have some evidance that Joe Gillings (owner before last) did a ring and piston change at 9500KMs, she now has 23000kms on the clock, asumming they are correct when should i look at changing rings, and or doing a top end rebuild, barrels plated, new pistons, etc etc, is it expensive, who can do it, ? any advise appriciated