CATBACK EXHAUST HELP

Got the GTI MK6 2013 in January this year.

I'm stage 2 tune, downpipe, and APR intake.

any advice on catback?

Do i need to buy a catback that is 3" or can 2.5" work?

My brother said I need a midpipe..does this come with the cat back ?

Your downpipe is most likely matted to your stock catback, which would lead me to believe your downpipe has a 3" to 2.5" reducer on it at the very end. That means you'd want to get a catback that is 2.5" in diameter. Otherwise if you got a 3" diameter catback it would mate up. You would need a new downpipe end piece that is a straight 3" pipe....hopefully that makes sense.