If you replace the factory manifolds with their integral pre-cats, you may need to fit a catalyser elsewhere in the exhaust system.

We needed the best catalyser in the world to handle the power outputs and pressures of the supercharged V6 - it had to be the HJS HD version. This 130mm diameter 200cell catalyser will pass any emissions tests while presenting minimum back-pressure to exhaust gas-flow.

Two bosses are welded into the exit cone of the catalyser for the repositioned sensors.