One of the common issues with the MZR motor is the weak OEM VVT Actuator. These are known for going out and Mazda has revised the OEM VVT actuator to make it stronger and keep it from failing.
How can you tell if your VVT Actuator is failing?
You will hear a rattle on start up coming from the passenger side of the motor.
What's happening is the actuator can't hold oil pressure and therefore it can't take up the slack in the chain and allows it to hit the timing cover. This is the first sign that your VVT Actuator is going out and you will need to replace it quickly. If the car slips timing, pistons will meet valves and you will be left looking for a new motor.
If you are only looking for certain components in the kit, use the list below with links to each individual part.
Items Included in the Kit:
Mazda OEM VVT Actuator (newest revised version)
Mazda OEM Camshaft Bolt (added 5/6/15)
Mazda OEM HPFP Cam Housing Gasket (added 7/8/16)