Hi guys,
I had a search on the forums but couldn't find the info I was after, so hopefully you can help me

I have a MK4 Golf and I am looking to remap the ECU. I was looking on the R-tech site which seems to have been recommended a lot on this forum, and noticed that I have to select 1 of the 4 options.
1.8T_20V_150BHP_AGU
1.8T_20V_150BHP_ARZ
1.8T_20V_150BHP_AUM
1.8T_20V_150BHP_AUQ
What are these 4 different types and how do I find out which one I have?
Sorry if this is basic, I love to drive buy my tech knowledge on cars is embarrassing!
Thanks in advance
James