The John Cooper Work tuning kit (JCW) wasn't a simple upgrade on the last-generation Mini Cooper S: it was labor-intensive to install and included expensive items like a new supercharger and cylinder head.
The JCW kit for the new, turbocharged Cooper S is much simpler. For $2100 plus installation costs - around $200 at your local Mini dealer - horsepower takes a modest jump from 172 hp to 189. Maximum torque is also bumped slightly - from 177 lb-ft to 200 lb-ft. These increases are the result of a redesigned air box and high flow air filter, a low-restriction exhaust system, and a reprogrammed ECU.
We're excited to try a Mini fitted with the JCW kit and plan to add it to our Four Seasons Mini Cooper S in the coming months. But most of us around here feel that $2000 is a lot to pay for 17 hp.
Some performance numbers from Mini:
| Test | Cooper S | JCW Kit |
| 0-60 mph | 6.5 sec | 6.5 sec |
| 50-75 mph, 4th gear | 6.4 sec | 5.3 sec |
| 50-75 mph, 5th gear | 6.7 sec | 6.3 sec |
| 50-75 mph, 6th gear | 8.9 sec | 7.6 sec |