EASY it goes on those header fasteners. It does not take much to strip the stud in there! Would trust only the best & recently calibrated torque wrench on those --' otherwise...it is just snug for what? a 10mm /12mm nut? On a LIKE200i that stud is pretty slim. And has been stripped with a torque wrench.
Noisier now?......please post an audio for your fellow 150i owners to comment for your peace of mind? Or swing by your dealer and let them hear it on the center stand.
I know the CVT gets less quiet as it gets some time on it. Rollers banging around, belt slapping a bit, etc.
Stg