Hi Tony, I bought my XTZ new and was a little disappointed with the fueling and throttle response at low revs. But now after 11,000 miles it is getting better, it pulls from lower revs with out complaint and I do not notice the vibes at high revs.I have just replaced the cush drive rubbers but no other mods, how many miles has your bike got on it? Stick with it , it will grow on you Steve.