Liam225 on here had the spec 3 on his car and it is very loud. i have the old pro spec on my car and have done for over a year now and i use it every day, love it. the new pro spec (now named the pro spec 3, strangely) is much quieter, my flat mate has it on his ep3...so stay away from that one.
if you want loud, buy an old pro spec or old spec III, Spoon N1 or J's racing. all other exhausts i've heard dont compare at all really. i have the buddyclub manifold too, and since my car was mapped i get lovely burbles and pops on the overrun.
AEM V2, i bought this kit originally before changing to the 'M'... in hine sight i wouldnt have changed. the V2 is a great piece of kit and i would recommend it highly, people speak about heat soak but it will only be affected when on the dyno, in the real world, the air flow is so much greater and it will never happen. my flat mate's EP3 has my old AEM V2 on it and he just came back from TDI having made 252bhp.... !!!