Please post the dyno sheets and log some data. it is difficult to say ANYTHING about your results. Without the supplementary data the opinions here are conjecture. Go back to the same dyno and log the following at a minimum.
If the DME is reading IATs north of 100* F, this could explain your low numbers as the car will pull timing and the power will be neutered. Now if your IATs are within an acceptable range of ambient (15-20 degrees F) and these are your results, I may have concerns. You would be shocked how playing with the cooling fans can impact your results.
p.s. On another note, Dinan tunes have been notoriously conservative since the E36 days. Have you considered a more reputable E9X tuner with VANOS and cam control for your car? Ahem... NickG, Evolve, BMP?
Ground Control - Vibra-Technics - CSL Roof - ZHP steering rack - Evolve Airbox/tune - 4.10 - SS Stepped V1's w/ HJS Cats - SS Res. Sec. 2 - Borla mufflers - Rotora 4 pots - PFC DD rotors - Morr VS8.2's w/ 255/275 Pilot SS