I wouldn't go to such extremes yet fella and would suggest that a quick search through the main tuners will pull up some dealers in Mexico.
I just took one example and found that APR have a distributor down your way;
Autotecnica Pits, S.A. de C.V.
Tiburcio Sanchez de la Barquera 37
Col. Merced Gomez
Mexico DF 03930
Tel 01 (55) 5593-9384
The above is one example and I would suggest that you look at some of these other sites for products and dealers.
APR -
www.goapr.com - Very well known both in Europe and the States and stage III tuning gives very good figures.
GIAC-
www.giacusa.com - Again another well known tuner in the states.
Neuspeed -
www.neuspeed.com - Well known in the states, but less so than the two above.
Greedspeed -
www.greedspeed.com - I don't know much about these guys but the Yanks do from what it seems.
TAP (Total Audi Performance) -
www.tap1.com - Again I know nothing about these guys but they do across the water
AmD -
www.amdtechnikusa.com - Newbie to the States, but based on the European arm will provide good products.
Forge Motorsport -
www.forgemotorsport.com - No chip tuning of their own but they do offer a number of great tuning products for VAG cars.
I found GIAC also have a dealer in Mexico.