Just googled the rules:
http://www.idpa.com/compete/rules
8.1.6. Legal Modifications for All Divisions
8.1.6.1. Storage locks may be disabled or removed.
8.1.6.2. Magazine disconnects may be disabled or removed.
8.1.6.3. Lasers that are incorporated into the firearm or sights are allowed if they comply with all other division rules and the laser is not activated during a string of fire. Tape may be used to prevent the laser from projecting.
8.1.7. Non-IDPA-Legal Modifications for All Divisions
The following features and modifications are not allowed in any division unless otherwise specifically allowed in the rulebook.
8.1.7.1. Compensators of any type including hybrid or ported barrels.
8.1.7.2. Add-on weights for a competitive advantage. This includes (but is not limited to) weighted magazines, tungsten guide rods, brass magazine wells, weighted grips, and weighted grip plugs.
8.1.7.3. Heavy and/or cone style barrels without a barrel bushing except as allowed in ESP and CDP divisions with length restrictions.
8.1.7.4. Sights of non-standard configuration (ghost rings, Bo-Mar ribs, etc.).
8.1.7.5. Disconnecting or disabling of any safety device including (but not limited to): manual safeties, grip safeties, firing pin, striker, and hammer blocking safeties, 1911 series 80 firing pin safeties, 1911 Swartz safeties. 1911 series 80 frames may be used with series 70 slides or vice versa. Revolver actions may not be modified so that the hammer can fall when the cylinder is open.
8.1.7.6. Lights mounted on firearms.
8.1.7.7. Rail mounted lasers and bolt-on trigger guard mounted lasers are not allowed.