I am running 254deg cams in my CG13 which are very close to the Tomei profile. We advanced the timing to the point of losing power and didn't reach detonation. There isn't enough compression on the standard engine to maximise the power potential of the cams. If you haven't already, you'll need to use bigger injectors, as the standard CG13 ones will be on their limit.
Plenty of gains to be had from a good fuel map and also healthy gains from a good ignition remap, (compared to the standard ecu). You wont however get the most out of the car with a piggyback ecu due to the standard ecu's fuelling management....but not all of us are up for standalone management.