If you are only running front speakers then check out the Micro amp manufactored by Elf Audio for about $199. I know its an off brand, but its a secret in the Harley Davidson community. You can mount this tiny A/B class amp almost anywhere and its got about 75w per channel. Also, it may be ELF Audio brand but in fact ARC designed and developed it at a much higher cost. Get the Elf unit for about half of what ARC wants.
The amp is just a tick larger than 5x7x2 inches.
2 Ohm stable
Elf Audio page:
elfAudio
ARC Audio page: NOTE ARC actually sells a 4 channel version.
Arc Audio
ACR vs ELF Audio comparison:
Mini Amp Debate..... Elf-Arc guts pics - DIYMA.com