When I bought my A4, I knew that it had an ECU upgrade; but how do I know what type or brand that I have? Where can I look to find out? How do I know if it has a security feature?

I have these questions because I am having a hell of a time with a combination of turbo lag, potential "limp mode" or something similar, and constant surging. I am trying to narrow it down to figure out what the hell is wrong. What could it be?

 

open up the ecu and see if there are any brand markings on the chip.
http://www.fastaudi.net/library/ecu_remove.html

You'll need a torx bit to take the ECU itself apart

 

you should get a boost gauge so you know if you are actualy surging or in limp mode or whatever. and a k03 doesnt have much lag to speak of.