We supply them in case you want new. Feel free to PM me if you need to order. £399
Details here: http://www.350z-uk.com/topic/93525-torqen-lowest-price-370z-exhaust-upgrade-options
Spoke to Design911, they're in the process of moving premises, but they say about 6-8 hours to do the job at £75/h.
I'll be doing this myself at some stage, car is still under warranty at the moment, so I can't be bothered
Nicest explanation of the IMS problem and the easiest solution to it:
http://www.pedrosgar...hnoFix_DOF.html
Also available in UK here: http://www.design911...997/prod127607/
Installation instructions here: http://cf-design911-...uctions_DOF.pdf