Not a problem, glad to hear that your enjoying it... Not wasting any time with mods either ... NICE :)
I looked at importing the exhaust initially but wasnt worth it as shipping costs alone was 950... Once you add taxes etc not worth the effort. Think it's around 2800 fitted from Chatswood which was a no brainier, great service and covered under warranty for peace of mind. I'm sure the Brisbane dealer will be able to get one on for you. Definitely have a listen to it first before you commit as its not for everyone .. That said it sounds mean. Very different to the C63, doesn't have the over run bark like the merc but has a deep burble at idle and at WOT sounds like an angry lion being kicked in the nuts :) - the auto blip downs do sound amazing after the exhaust, my favourite part... If you can live with the drone I have no doubt you will love the sound .. Esp if you're missing the C63 ambiance ;) I personally don't miss the clunky slow gearbox ...
KW's are great just make sure you get them installed and tuned properly, can be a bit fiddly adjusting. Any reason you opted for 20" ? What did you get?
Mike