When my 3 Door is running at the moment the Voltmeter reads 13.6 and then drops to 13.1 when you put the lights on.
Does this sound a little low? I swear it used to charge at about 14 Volts a while ago.
Just wondering if the alternator is on the way out.
Rich

 

sounds fine mate,

if you fancy a job which will better the charge, replace to alt-battery wire, as it gets cooked by the turbo and gains resistance.