Hi there : )
I don't think that you will find many chip fan here in the f34 forum
But if the 28i is not enough for you and you want some improvement I would strongly suggest you to go with the ac schnitzer performance kit which contains a new intercooler and a catalyst also. Ac schnitzer upgrades won't risk your original warranty.
http://www.ac-schnitzer.de/en/bmw-ca...4/engineering/