ECU Tuning, Nozzles and Tuning Boxes
Volkswagen
Chips and ECU Tuning - this modifies the coding in your ECU
Aligator - custom ECU tuning located in Canada
Rocketchip - Jeff’s site is out of date, so best to head to TDIClub and drop him a PM through there. He’s slow, but he’ll respond - he’s just that busy. 
Technine - Canadian focus ECU tuner
Upsolute - caters to European, US and Canadian marketplaces
Standalone Tuning Boxes - this does not modify the ECU settings, but dumps more fuel into the cylinders
PSI PowerBox - UK focused company
Tuning Box - looks to be European based, but caters to North American market as well
Van Aaken - well regarded tuning box manufacturer
Uprated Nozzles - the larger the size holes in the nozzle, the more fuel pushed into the cylinder. Nozzles alone will yield an immediate and obviously noticeable difference in power output.
US
Fratelli Bosio - very high quality nozzles - specify sizes and be impressed. Expensive, but folks rave about them.
Sprint - also high quality units
Canada
SMOG - lower cost alternative to the better known names, but one of the best cost/benefit ratios around. Tough to go wrong for about $140 Canadian.
As with any modifications, please be sure to consult your local rules and regulations to understand if what you are doing is legal. There are also insurance considerations as many companies will not insure modified cars. Be careful, as well, as a replacement clutch may be needed with increases in power. Many models will need a new, higher rated clutch if nozzles and tuning are both performed.
