Or will I have to have one custom fabbed??

 

Crap...just posted a reply...anyway, there are quite a few out there, just depends on your patience, how badly you want exclusivity, and what you're willing to pay. In no certain order, when I was looking I found:
Supersprint
Milltek
Eisenmann
ABT
Stebro
Oettinger
EBay (in germany, .de)

And RS6 variants, that require a little modification:
Remus
OEM
B&B

There are more, too!

 

i have the supersprint exhaust on mine and am quite happy with it, another person I know has the Miltek, they are both quiet under normal driving conditions but when under w.o.t. they givea good sound. No sound clips sorry. Doubt this helps, but I tried

Andy

 

2nd that on the Miltek, My friend has that system and it sounds great.

 

I hear Milltek, but I haven't made the plunge quite yet.

 

i think also MTM has an exhaust for the 4.2l
thats what i will get for mine
also is there a supercharger for the 4.2
i found one but its 10k