Description Reviews MINI Cooper JCW Exhaust manifold for the N14 or N18 engine. If you're Installing a stage 2 kit think about this JCW exhaust manifold which offers better air flow over the standard Cooper S manifolds. Not only does it flow better, it makes more power, it is 2 lbs lighter than the stock unit. Any time you can save weight, it helps you in handling and power to weight ratio. Ready to bolt on and will work on either the N14 or N18 engines.