@fathead: we achieved best results in the NTC3 when we ran the dual-chamber pipe with a header which is cut by 10mm!

Also there's a new, shorter version, of the associated dual chamber pipe coming which was in use at the worlds in brasil. not sure when it's going to be released tough, but our engine liked this pipe a lot since it already has very good bottom end and therefore doesn't require a very long pipe!

but you'll be ok with the normal dual-chamber pipe and the cut header. that's the combination our drivers use also.