With the ECU remap, the expected HP and torque increase are 10-13 Hp and 20 NM respectivelly. Not really that much increase lah and don't know can keep up with those with BMW performance parts

For our NA engine, further upgrade in power will be a challenge. I was asking Freddie on the force induction option or stroker kit, he advises against the first one and the second one he has no direct experience to do it on E90. I saw the stroker kit upgrade previously here but probably need to understand the implications and risk before considering.
Otherwise, the next upgrade will be on things such as wheels. BTW, what do you think about BMW Performance wheel 269 or Neez Euro cross super?