Hard to say, there were no "stock" minis out there
I think the closest to stock was one with an x-speed motor and stock fets. It was considerably faster on the straights than my box-stock dNaNo, although through the twisty sections I was able to keep close to pace.
We clocked some laps with a stopwatch, not exactly the most accurate method but to get an idea. The best lap I turned was a 9.3 and I think the fastest laptimes for mods on that layout is around 6.5 seconds.
Stock, the dNaNo feels good on a mini96 track, 2 tiles wide in the turns and maybe 3 wide on the straights with the expansion pack. On the fullsize RCP with 50cm tiles 3 wide in the straights and 2 wide on the turns the car felt really small and slow. There was only a small amount of hop from the seams in the tiles, but I think if you were to get the dNaNo up to speed with some mods it might be a bigger problem.