Default [Q] Safe level of OC? ElementalX Settings?

I would like to flash the Elemental X Kernel over CleanROM, and I am interested in slight OC'ing. I notice with the installer it sets the boot CPU and GPU to what you set it to during the install.

If I use trickster mod can I go back to stock if I set the cpu to 1.7ghz in the install?

I figured 1.7-1.8 would be a mild OC and no more than the preferred 450 for the gpu. What does everyone else use? I game a lot on the nexus but don't want to overheat the device too much.