In ye olden times throwing down the gauntlet was apparently a way off challenging someone to a dual. Today, saying the gauntlet has been thrown down is merely stating a challenge has been made.
As you finished first and exceptionally well for a first attempt, I (by saying the gauntlet has been thrown down) stated you've challenged all of us to finish and to a high level. Er, not that we wouldn't shoot for high levels anyway, but, uh, well nevermind. You get the point I think.
I'm somewhat suprised it needed explaining as it's always been a common saying as far as I know. But then again, what do I know?
AM = aftermarket. There are suppliers who provide accessories you can use to upgrade your model, such as spark plug wires, cast aluminum wheels, aluminum brakes, and so on and so on. Scratch = scratch building. Some of the more MacGuyverish among us will build additional detail from raw pieces of plastic or whatever we can get our hands on.
Some of the lingo is a little confusing, Pinkranger, so don't hesitate to call someone out on their babble.
Once again, nice job.