from what a remember r-tech are very funny about mapping cars with the DV+ , surely thats for a reason ?The A3 is a more difficult proposition with any of the DVs as it is mounted on the turbo rather than round the front of the engine as on the S3. The top bolt is quite tricky, be sure you have slimline torx drivers and Allen keys before attempting anything regarding the DV+.
I have the DV+ and it works very well. I fitted a new G revision to my son'sTT and in some ways regret it as eventually it will split. However the original was a none split G with 23k on the clock and so it should last fairly well. R- tech suggest the best boost comes from G but it is a service item with tuned engines. The Forge valve does away with the electronics actuating the valve and you have to install a vacuum pipe to actuate the valve. Fit a rev D if you want to forget about it but some leak from new around the piston and I have read that this might be the equivalent to a 6mm hole in the FMIC!!
In my case it caused a sudden loss of power when quickly coming off the throttle and back on again under heavy load and WOT. This sounded like it was due to the turbo stalling which I can only put down to being the DV+ for some reason under those conditions not venting the boost pressure fast enough forcing the air back through the turbo when the throttle is closed suddenly (exactly what a DV is supposed to prevent).
I didn't keep it fitted long enough to consistently replicate the issue as it put me right off straight away!
I took lots of time ensuring the piston was running up and down perfectly in the cylinder of the DV+ using a good coating of oil. I also gave the springs a good coating so that there's no friction build up anywhere in the unit. I have seen posts where some people lube the plunger and not the piston.
User error has a lot to answer for in situations like this. When all else fails - read the instructions!!!