Meanwhile,
I changed exhaust's rear bushing from an old original to powerflex, gaining 120gr

.
I wasn't expecting any noticeable difference but there was.
An annoying buzz at 4000rpm was eliminated but a vibration (like massage) appeared during idle.
Overall, definitely positive !
Also I have cut the central mirror to keep the mount, and glued it to a huge curved panoramic one (10gr lighter).
The idea is to delete the passengers mirror for weight and aero gains, and as you can see, the new panoramic, covers more area than the old central and the passenger's combined.