the biggest thing for the 1.8t seems to be a chip, or if he wants a lot more power and has a lot of $$ go for a KO4 turbo upgrade kit complete with a chip. this will boost power a lot. people who do the Ko4 sugest an intercooler as well.
check out www.ecstuning.com for some great parts
check out www.ecstuning.com for some great parts