Magical Traps DC and Disable Device

[Mavrickindigo]

I am working on increasing the CR of some encounters, and am now trying my hand at buildilng stronger traps for my party to go through. I have a Shocking Grasp trap that is CR 2, and so I'm deciding to use a higher-level spell to make it a more powerful electricity trap.

Problem is that looking at the rules on this srd http://www.d20pfsrd.com/gamemastering/traps-hazards-and-special-terrains/tr aps there seems to be no rules for determining the CR of a magical trap based on perception DCs and the like. Do the DCs and Disable Device checks not affect magical traps like they do mechanical traps?

[fretgod99]

DCs for Magic Traps are set by spell level (specifically, 25+spell level). The DC is set by the highest spell in effect. If you want to increase the DC for a higher challenge, consider using a higher level spell that creates a similar effect, an additional spell on top of the intended effect (perhaps an illusion or pit, etc.), or have the trap be created using Heighten Spell to effectively increase the spell's level.

EDIT: Sorry, forgot to add the bit about CRs. CRs have modifiers based upon spell level, average damage done, etc. There are charts in the Traps section of the Environment chapter of the CRB. So heightening a Shocking Grasp spell could increase the DC due to spell level (if heightened enough) or average damage (if heightened enough).