Gameboy Color extreme overclocking

Costis is screwing around with the clock on a GBC and I just couldn't keep myself from trying it out. He quoted some pretty insane max clock speed and I wanted to see whether it would really go that high. Turns out it goes pretty high: ~24Mhz (~3x) for GBC games, and ~48Mhz (~6x) (!) for GB games. Normal speed is input, though GB games internally run at half speed (~4Mhz), which is why they can run much faster. This is just a GBC hooked up to a frequency generator implemented on a Spartan-3E st