Dont go repro, the ZR1 OEMs I got were pretty damn cheap ($1395) and you cant really beat the performance for the price. Got them from Bob and HOW.
2014 ZL1 Speed Inc Building
2011 E92 DCT ZCP Stock
2009 Z06 Speed Inc Built
2008 E90 6spd ESS-Meisterschaft GT-AA Catless X-Volk TE37