A chip is not going to give huge peak gains, a well setup map will offer a sharper crisper throttle respose, smoother mid range from added ignition advance and a rich burn, You will maybe gain 4-5bhp across most of the midrange power band, and this is muc better than having 15bhp just on the peak around 5700rpm.
Cams cannot be fully setup via the mapping, you will need veriner pulleys to allow the vavle lift and over laps to be dialed in, just by getting the cam setup correct on a rolling road can easy give you and extra 4-5lbft and 4-5bhp, get it wrong and you can be left with a massive off cam flat spot, and sweet cam duration comming in to late and the rpm band. And when the valve timing and ignition advance is spot on the car will sound sweet across the whole rpm range.
For a morning tuning session, valve timing setup and software remap on the rolling road using the load will be around £250 all inc