Mine was built during Dec last year and reg this year. I visited during build and got to chat to the guys doing the spanners....
As far as i know no real changes although i understand the exhaust mounting rubber blocks are of a larger, more robust design. Not sure when that changed.
I drove the brooklands factory demo car during Oct and that did have louder ( brooklands) exhausts - very nice sounding indeed.
So the direct reply is no changes yet - i imagine its still currently 2014 model year. Then again no doubt improvements/changes go on all the time.
What colour/spec etc did you go for Grockle??