Here is the way to decode the Engine number to find out the manufacturing date Of Xtreme.
Suppose the engine number is XXXXEEYZXYYYYY
Y is Year of manufacture
X Is the month of manufacture.(Here the X refers to the one after Z)
Z is the location of assembly plant.
XXXXEE is Engine description
YYYYY is the serial Number.

Year :
A = 2010
B = 2011
C = 2012
D = 2013
E = 2014
F = 2015
and so on.

Month :

A = JAN
B = FEB
C = MAR
D = APR
E = MAY
F = JUN
G = JUL
H = AUG
J = SEP
K = OCT
L = NOV
M = DEC

Plant codes :
G=GURGAON
D=DHARUHERA
H=HARIDWAR

MY Xtreme's Engine code read as XXXXEEDGBYYYYY(Other characters blanked out due to security reasons) which means that it is manufactured in February 2013.
G means it was assembled in Gurgaon.

The other way to check out the exact manufacturing date is from a VIN sticker on the rear number-plate. If one finds this sticker missing/Or a TR sticker stuck on top of this, then the bike is surely from an old stock as the dealer is hiding this VIN sticker from you.