I have an RS6 w/Revo & APR Transmission Chip--otherwise stock. I have had zero problems, however recently I have been experiencing inconstant boost at low RPM’s. Its almost like extreme turbo lag or "skipping" of RMP's. What do you guys think? I have been doing a little research and was wondering about the N75 and/or DV valves? If so, which one would I need?