I haven't bought one for my mk5, but I bought a Powerflow stainless box for my mk3. It was less than double the price of a standard one, but came with a lifetime guarantee. The plan was to buy each section in stainless when it needed replacement until I had a full system, but then I changed cars.
If (like me) you don't want to attract attention, then ask for it to be standard specification. You can't tell the difference.
I'll definitely do it again when the time comes on the mk5.