Hello, I have been reading the good info on xr's but I have a question. I can buy a 1991 xr600r for a good price, looks clean but it has a "powerup bigbore kit" the owner told me about. The question is three part. 1. Does the supposed"power up kit 630cc?" hurt the reliability of the bike? 2. How will this bike do on the highway(35 mile stints). 3. does this year and model(1991 xr600r), have any issues I should look for? Thanks in advance!