Just to get people wound up, a tuner (or if you're an american, tunor) I speak to alot over in the good ol' US has always used Dynapaks he used to use one at a local place to him where a stock car made ~150 at the hubs. He then bought his own Dynapak, put a couple of stock cars on and they were all reading in the region of ~115 at the hubs.

Moral of the story? Use the same fucking dyno