Good question, since your X1 shares the same engine as the 335i I would post on that forum... I don't think anyone here has gone with either tune in an X35i yet, or at least hasn't shared.
We have the BMS stage 1 for the N20 engine and love it.
SOLD Mineral Grey Metallic X1 s28i M-Sport
for sale: BurgerMotorSports Stage 1 tune
Last edited by greyX1; 06-26-2013 at 01:40 PM.