PS, (In case you don't know) Make sure that all the speakers are in phase. ie, all positives from amp to positives on speakers.
They will work either way, BUT speakers will cancel each other out a bit if, ones moving out as other's moving in (if you know what I mean) Especially important if you have rear's as well.
Get some silver backed sound deadening sheets or large rolls (similar to dynamat) off ebay or somewhere for front doors, rear doors/wings and boot floor&tailgate to make it sound better. This will cost £50 to £150 unfortunatleyÂÂÂ
Takes a few hours to fit too! but done carefully will make a huge improvement. Take all your seats out to do this 1st. They remove easily (5min job)
Use decent thickness MDF if you're making sub enclosure and make it solid. Don't use 3/8" thick, that's too thin. Need 1/2" thick minimum. Sealed enclosure needs to be 0.75 cubic feet. Ported normally twice as big. Finish with some nice acoustic cloth (again from ebay or somewhere cheaper than stereo shops) Take time to securley fasten speakers, etc. GOOD INSTALLATION & quality wiring makes the difference.
oh, and one main thing after all that's done.... Post some pics!ÂÂÂ