I have just bought a 2001 A6 Avant quattro sport 2.5TDi V6 180hp. It has a very sluggish pick up from a standing start, say anything below 15-1600rpm. Is this typical or is there something wrong? Absolutely flies once moving but I'm very wary of pulling out in front of anyone. Does fitting a Tunit/K&N filter improve the low engine speed response?