well, after playing around with the exhaust yesterday and taking different parts off, i've come to the following conclusions:
1) i can safely say that you could easily leave the resonator and take the two rear mufflers and the sound would be as loud as a normal 'hoons' car...
2) running nothing after the cat would result in you getting fined within the first 2mins you're on the road... if there is a cop in a 10km radius from you, they will hear you and come and get you!
3) if you're planning on doing it at home, make sure your neighbours love you!!! lol
4) with only the cats in place and no other sort of muffler/resonator, the car sounds AWESOME!!! much like darius's clips, but about 5 times louder and it had a real bark to it...
we took some clips of the car at different stages, but it was on my mates camera, so i'll have to wait till he emails them to me...
here is the resonator: (looks to be roughly 7" in diameter :o)
here is the cat: (looks to be a fairly decent cat which would flow really well)
here is the merge collector thats look nnnaaasssssstttttyyyyyy!!: