did we ever figure out your answer?
a two step is only really used on a turbo car, probably could use it on a sc car but it allows you to have two rev limiters, one with the clutch out and one with the clutch in. so to build boost, instead of redlining it and run the risk of damage and blowing the tires off when you launch, you put a two step in and if you build max boost at 3 grand then you set it at 3,000 so its like a pretend rev limiter so you build max boost and you dont have to watch your gas and hold it at a certain rpm, just floor it and go.
two step is an aftermarket item but with the SS they sorta have that system with the competitive mode.
as to your LT1 comment, my buddy has one and yeah they dont have a rev limiter. but when you hear it tacking out its because its the actual limit on the rotating assembly and it simply cant spin over any faster
1000 = Order Placed (11/16/2009) RS Constraint
1100 = Preliminary Order Accepted (1/9/2010) Order # NSPHF8
2000 = Accepted by GM (1/12/2010)
2500 = Preferenced (1/12/2010)
3000 = Accepted by Production (1/13/2010) TPW = (2/8/2010)
3100 = Sequenced (1/29/2010)
3300 = Scheduled (1/29/2010)
3400 = Broadcast (1/29/2010)
3800 = Produced (2/10/2010) VIN # 2G1FG1EVXA9192608
4150 = Invoiced (2/11/2010)
4200 = Shipped (2/12/2010)
5000 = Delivered to Dealer (2/24/2010)
6000 = Delivered to Customer (3/1/2010)