Just a word of caution.
When you get your bike modded to pass the ULEZ emissions they tell you to download the TfL Drive app which you can then enter your Reg. Number and it will say "Nothing To Pay -Exempt"
Well, lo and behold, that app has crashed, and sends you in a loop for a software update that doesn't exist.
Tried uninstalling and reinstalling but that never worked.
I've seen it myself that my bike is exempt and have the Dyno records, but when I tried on a different website it takes my bike as standard and says It is NOT exempt.
I'm sure it will be okay, but I better not get a fine through the post, because I will not be impressed.
Although my mate just told me all the cameras on the main road near where I live have had the cables cut.