I remember years ago , the company I was flying on that time for, started receiving fines in Manchester, I guess when departing from rwy24. The problem stood with track during a turn.
There were no speed limits on that departure, so pilots used to do it nearly 250kts. Company released a circular restricting the speed to 220 or less and we had never had any violation again.
Stupid? Yes, because the SID should have a speed limit, but it was the way we managed to solve this problem.
Though it shouldn't have been a problem - after all you were flying the SID accurately, at a legal airspeed, weren't you ?
Most, if not all, radar-driven track monitoring systems work by comparing your flightpath with an imaginary line on the ground (e.g. in the UK, the edges of the NPRs). Of course a SID is a procedure, not a path, so that clearly the radius of a constant-rate turn, and therefore your track over the ground, can be expected to vary with airspeed.
In theory the width of the NPR swathe is supposed to take into account such variations, but I recall querying with the CAA a couple of years ago some of the saw-tooth edge coordinates of the NPRs in Heathrow's NTK system - the response was that nobody could remember who had originally plotted them ...