First, let's take a look at the EAS graph. On their dynojet and with 91 octane pump gas they hit 226.51 wheel, strong:
Here is the graph from Insideline also with 91 octane but on a different dynojet, 240 whp:
So, why the disparity of about 14 whp? Well, the dynojet Insideline uses is routinely seen providing optmistic numbers. Yes, all dynojets are not created equal. We feel the numbers from EAS are for more realistic and will be much closer to what others will be hitting with their baseline graphs.
Notice when the Z4 dynograph and the 328i dynograph are overlaid they basically mirror each other with the same dips and same curve. No change in tune in stock form, all N20's should look basically the exact same with variances due to wheel weights and transmission choices:
The N20 is underrated quite a bit. This is likely done to keep 335 owners happy as the N20 does not give up all that much to the N55. This is going to be an exciting platform to tune and we should see the 300 whp barrier passed with this motor fairly quickly. 300 crank will be passed basically instantly with the very first set of tunes meaning an N20 with a tune will be a 335 killer in stock form.