So, if I call it and hit metal, then +2. If I call it and hit an ace, then +6. However, on either miss I would be -2.
Also to be clear, the second round option only affects the Metal Muncher Side bet. In other words, who ever wins Ace Race does not necessarily win the side bet and vice versa. SO, if you take the side bet, it is very important to circle your gambles during the second round. We can figure the points with and without the option only if cards are marked correctly (or at least it really helps).
Gonna be fun