Installation (and coding?) of N55 Powerkit

[scaramanga]

Hi,

I’m about to purchase a 135i N55 E82, as I feel as if I won’t be able to afford another 1M.

I’ve been able to source the factory N55 power kit, and just wondered if the upgrade can be coded by an independent garage or needs to go to BMW. I think the powerkit comes with an ‘unlock code’ which the dealer can apply to the car ?

The car has a production date of May 2013, which I think makes it harder to flash ?

I know the fan/DME/cooler can be installed by an independent but I’m just concerned about where/how to get the coding done.

Am based in the UK, so any advice would be most welcome.