I have just bought my 1st BMW, 2008 335xi coupe with sport package. I see this CF chip , claims 60_ HP increase and 4-7 mpg improvement...need some feed back has anyone tried this ?????? My dealer said they would put in but if something went wrong and could be asigned to the chip add on then my 100,000 mile warrenty could be effected , if they traced to the add on chip.....anybody know anything????