Ahhh, my buddy has the game. I haven't seen 450's or 500's, but he wants to unlock everything himself. Haven't even seen the SuperMoto part, yet. A fellow hillclimber (Youth #1 Many times) said the code is "Too Lazy" to unlock everything.
By the way my Favorite polish is Wenol for hand rubbing, and Black Diamond for buffing wheel. Mother's is great for chrome or previously polished parts, these others work on oxidized Aluminum very well.
Even at $120, polished parts are a good deal