Lin, yes the chip is a good investment. To really get your moneys worth, though, I'd let Colter get it custom-burned if I were you. That way, it will take better advantage of his current changes to the car (exhaust, intake, etc.).
Think about it this way - the Contour came w/ Windows 95 installed. We all know that wasn't any good, so some have upgraded to Windows 98. Well, Colter is late in the game, so it's like he'll be upgrading to Windows XP (if he gets the DiabloChip). So in actuality, by holding out this long he's getting a better product than the early adopters.