I've been reading on the Launch Control system. From what I can tell it was first released in the 2010 model year. If you had the manual trans, you put it in competitive driving mode, push the clutch all the way, push the gas all the way and it would kick in a rev limiter around 4000 RPM. When you drop the clutch the traction control system would try and give you the best traction it could so you get consistent launches at the drag strip.
My 2008, of course, does not have this mode. But, I can add the 2-step module. From what I can tell about this module, it's basically a rev limiter when it's enabled, which would be when you push the clutch in, unless you just wire a switch to enable it. So any time the clutch is in you can't go over the set rev limit of the module.
That all makes sense to me and seems pretty straightforward.
I was reading the manual on the mode selections. When in competitive driving mode, it says all the traction control and driver assist is off. So if you had a 2-step, I would expect when you drop the clutch that the tires would probably break loose and since the rev limit would now be off, you would rev higher and be doing a burnout. If you have the traction control system on, I would expect it to kick in and try to keep the car straight and not spin the wheels. I would guess this would give you the most consistent launches. Given my lack of drag strip expertise, probably the best launch I could expect.
What would happen with traction control OFF?
Am I right about my assumptions?
Is this how most people do it if they don't have a factory launch control?

 

I am an original owner of 11 GS 6 speed and my car has that feature. However I never used it once after seeing Ron Fellows driving school demonstrating in a video how to, and completely destroying the drive train with a loud crunch. I do not know what broke but the C6 would not move by itself had to be towed.

 

I've played with this function on my 11 GS and it isn't all that great. At a drag strip on a prepared surface, it may be much better but I have no experience in the environment. On the street or at an AutoX, wherever you are trying to use it, it revs to 4500 and spins the tires off the line. It seems to keep the car from just revving to redline right away, you can hear the ecm trying to find traction, not sure if it is modulating throttle or timing or both. I wish you could set the starting RPM, that would be much more useful. The system allows for a bit too much tire spin in my opinion. From the research I did, the consensus seems to be that it is not the fastest way to launch but is very consistent. If I were to launch in competitive driving mode without utilizing the launch control and the tires spin, it'll just spin all the way to redline as long as the car is going straight. If it gets sideways, stability control will kick in a bit. If you wanted an effective system on top of the 2 step, you would likely need something monitoring the wheel speed sensors and have access to modulate power output of the engine. I hope this is helpful.

 

I've used the competitive driving mode launch control one time in a secluded area and it did what it's advertised to do. However at the drag strip, I was hesitant to use it for the same reason gsflyer mentioned. With the added grip at the track, I was afraid to break an axle (or something worse).

To your questions though...

The good things about the 2-step are:
A. The launch RPM is adjustable
B. You can choose to leave traction control on or off, so you essentially get more control than stock launch control which must be in competitive driving mode. Folks actually do not recommend competitive driving mode for the drag stip. Ranger recommends the "traction control off" setting. You control the tire slip by how much you slip the clutch and squeeze the throttle. If you let traction control do that, you lose too much "umph" from your launch when traction control kicks in.

Check this page out: https://www.rangeracceleration.com/Launch_Tips.html

Ranger holds the #2 position on the stock Z06 fast list.