Went to have my 100 hour service done and my service tech calls me and says the exhaust tuner was melted. Asked me if my motor was runnin rough? I never had a clue, had it out the day before and it ran like always. anyone run into this before and what causes this? Tech says they have replaced a few already. Sounds like a big job and im glad its under warranty. Whats all involved in changing this out and how much would it cost if out of warranty?