all depends on what powerband you want. get the turbo maps and there is a formula out there (to lazy to bust out the book). once you figure that out just shop.
how much power do you want? you could go with something huge like a stage 3+ apr kit but if you can't handle it then it will be a waste of money. if you just want a little power you could try out a K04 kit which will just give you under 100hp but you won't be breaking the bank. you could even just stick with the turbo you have and for around $500 you can get an apr pr giac chip and that alone will jgive you around 50hp/75ftlbs and it only takes about fifteen minutes to install.
Search Volkswagen Jetta Questions
Volkswagen Jetta Experts