Whats the 'vtec engine' series based on though. Could well be B18C only?
5.2.1 The 2011 Honda VTEC Challenge is for competitors participating in any production based Honda car powered by any production based Honda car engine and does not necessarily have to have VTEC system. Forced induction is not permitted unless fitted from factory (at present this only includes the CTDI diesel engine). Drive layout must be the same as that car model had from the factory.
http://www.barc.net/images/stories/pdfs/regs/HONDA_VTEC_REGS.pdf
Various engines fall into different classes etc.