Non directional venting on front rotors is an ultimate fail (and cheap out).

As for your "slots" the direction does not matter, however we need to see the profile view to see which way the cooling veins are going.

Damn... grinding = fail in my book. Guess it's more waiting for a 370Z specific rear two-piece rotors.

The center-mount flanges for hat mounting to the rotor ring allows the ring to be used on either side of the vehicle simply by mounting the hat on either side of the ring :)

The hat can be mounted on either side of the ring thus making the rotor feasible on either side of the vehicle and making the venting slots/vanes perfectly directional if mounted properly.

The direction of the slots is directly associated with the direction of convergant cooling vanes within the rotor - With that said, direction of the slots do matter. The rotors should be identical on either side of the car. The hat will just be mounted on opposite sides of the rotor.

It might be true in this case but it is not consistently the case. Some manufacturers have the slots facing forwards even when the veins are pointing backwards, not sure the reasoning, just one of those variations between manufacturers. But yes, they should definitely be pointing the same direction on both sides.

so when ordering is their a left and right rotor, or do you have to take the rotor apart and put it all back together?

Left & right rotor? Each rotor comes pre-assembled.

RacingBrake
 

I purchased the RacingBrake kit for my 350Z. The brake kit included 2-piece rotors, calipers, SS brake lines, brake pads, and ATE super blue brake fluid. As I recall, these rotors are marked for each wheel so they are correctly installed.
I had no issues with the install nor any warped rotors after 30,000 miles.

Ya they are marked on the 370z as well, the rears require some cutting of the heat shielding* to fit properly. But I love my brakes now, very high quality stuff.

good info fellas, thx!

No. The hat just mounts to either side of the rotor.