To be honest alot of the standard level 1 maps provide the same amount of power, you cant stick heeps of power on these given its a dsg it would totally screw the system, correct me if I'm wrong but the 40bhp extra is the safest for component wear & this is what AMD, Revo & most others do on there base maps, warranty wise Dunk is right, maybe a Revo SPS dongle or Bluefin would be better so you can switch to stock/valet mode so its not seen, but to be honest I've not heard many people complain about the maps effecting warranty, I used to use revo all the time & I had the sps dongle, never once switched it of when audi did any work I ever used them for, its never been a problem for me, but its same with every car, it depends how you drive the car at the end of the day, if you constantly thrash it around then common sense prevails it will go wrong quicker, which is why my S3 was almost faultless, I used power when needed but didnt bang it around everywhere.
I think 3 I know of AMD, Revo & also Jabba are well respected on here, depends where you live.