Soupie,
If your car is Quattro then you have a 4Bar FPR fitted already /ubbthreads/images/graemlins/smile.gif
For a K04 upgrade that will be more than enough, you just have to carefully select your injector size for the power you require.
I think it's safe to say that you won't get big power from a K04 anyway, that topic has been covered many many times on the forum and those that DO have in the region of the high 200's BHP are running the turbo at very high boost and to within an inch of it's little life!
Either way, if you want more power and you want the most from the turbo and for the car to drive properly, you need to have the car remapped for the K04, it's not just a simple matter of bolting it on and hoping for the best! At the end of the day the turbo is shifting more air than the smaller K03s and will need the map adjusted to correct fueling accordingly.
As far as injector size is concerned, I really don't know what size the standard ones are on our cars (I THINK it's roughly 220cc, not sure) but again, I think it's safe to say they are pretty small.
You don't HAVE to change them for more power because whoever maps the car will get more power from it with the K04 than they will with the K03, obviously. You MAY get more if you use bigger injectors but you won't know that until you put them in and try mapping it with them in there.
Best of luck buddy.
T