I want to fit HSV R8 Headers to my 2005 VZ CV8Z Monaro. However the headers are about 250mm longer than the stock cast iron exhaust manifold . The cats are positioned right up close to the cast iron exhaust outlets on the monaro so I will have to cut them & move them rearwards by that amount & reweld them onto the then shortened pipes. Has anyone done a similar mod & was it worthwhile. I will still run the 2 oxy sensors on each side of the 2 cats but just move the cats back 250mm. Any help will help!!!!