Turns out I'm 2mm short on the drivers side due to a little ridge thats on the engine mount.......now I could slice this ridge off but that would be silly so what I'm doing is simply drilling the holes on the manifold to a larger size. Tomorrow I'll be up early and off the engineers supply shop so I can pick up a 15mm and 17mm bit. This means I can simply slide the manifold over slightly without having to cut the chassis (this is after bashing the manifold with a hammer btw! just to decrease the clearance needed)
The same goes for the passenger side but it is now leak free