whats the difference between the buddy club compared to the spoon n1 system in terms of loudness?
A true unsilenced B pipe and a Spoon N1 will be loud, as you have no real silencer after the cat. Buddy Club do a few different items.
Spec II - straight pipe all the way to the back (no rear "silencer" - even if the silencer is just a box for tone / volume shaping). Probably the loudest off the shelf exhaust for the Civic.
Spec III - very small centre silencer and a straight through back box, also very loud.
Spec IV - a clever design that muffles at lower revs but becomes a straight through at higher revs. Fairly sensible volume.
The II and III will give you raw touring car tone and volume, the IV is a bit more sensible. I have a custom exhaust on my car, as I already had an unsilenced B pipe so I had Advanced Automotive Systems of Newburn, Newcastle, make me up a backbox that looks like an angled spec III but has a straight pipe running to the tip, so effectively its a Spec II that looks like a III. It's seriously loud. It vibrates the air in your chest as you breathe, and conversation is difficult when you are getting your foot down. It pops and bangs regularly on gear shifts and on the VTEC, the noise can be heard well over half a mile away. It drones like mad too. Most people say it's "too much", and my friends love it but say that they wouldn't want to live with it. I absolutely love it.
I know you live around my way, you are more than welcome to come and have listen to it or come for a quick spin around the block to get an idea of loud. One of my friends used to have an Impreza with a Blitz Nur Spec R, which is one of the louder setups for Imprezas, and my Civic comfortably put his car in the shade in terms of noise.
http://www.youtube.com/watch?v=9q-nyMuMP5c
These 3 cars have Spec IIIs, and I previously suspected they had race manifolds and decats also. After fitting my exhaust, I now realise that an exhaust alone can get that level of volume. Note in particular the clip where they measure the distance you can hear the noise from as the car drives away.
I suppose theoretically, once you remove the silencers and get a straight through, you have reached a "much of a muchness" level of volume where a db or 2 does not matter, you have reached "properly loud" status.