welcome,
well lets see ,55mph on a 150 is about right
as for the 55mpg at full throttle, its close to the estimated mpg by TGB
eg;cruising speed vs rider weight & size = mpg
at 5400 miles your due for a belt anyway .
but when the v belt gets worn on the sides of the belt
the belt doesn't ride as "high" in both the variable pulley's
which basically means you don't get to the top speed the cvt can
put out.
now one other thing , depending on which r9 you have
you can have a BR8 -125 C.C. or a BR9 -150 C.C.
according to the owners manual
http://www.peirspeed.com/Cobrasales/docs/TGB%20Laser%20150%20-%20Owners%20Manual.pdf55mph is good for a 125 and about average for a 150
let me know if you want genuine TGB parts
oilyhans
i own a scooter shop with rentals ,sales& racing parts.
i also appraise scooters for KBB.
2003 Vino classic stage 0.75
de-reged stock variator w/8g sliding weights.
1.5k rpm springs
42mph
2005 veniceLX ~70cc~upjet~1.5k rpm springs & 7gr sliders
46mph
KeyWest de restricted~8gr slide