The 99-04 Cobra IRS was a by design, a compromised set up as they were designed to fit within the set confines of the existing Mustang platform. I knew guys who autocrossed them and the geometry was not ideal. A well set up solid axle Mustang does much better than they do with the 99-04 irs. About the only thing they do better is ride quality.Not great for drag. Better at pretty much everything else.