Firstly this was a very long time ago but
I started off with the R600 and cant say I ever noticed any difference in performance but I did have issues when trying to install a Stage 1 map, ended up having to revert to stock box. However I will still using the stock pipework.
Later on I changed it to the Revo Open Cone setup (for noise impact) which worked very well on a noise level but again no big change to performance (butt dyno)
I would stress in those days (and it was a long time ago) I did not do much track work so not sure if I would have noticed the difference there.
I then went stage three which means I now run a modified turbo and have the full Revo front to back air system (along with loads of other stuff) so the car has been setup to run on this setup but I have upgraded lots of bits to keep engine, dsg and oil temps down.