The owner of this F56 Mini Cooper S, John Cooper Works edition, travelled to us from London to have the JB4 and Milltek decat downpipe installed after seeing the YouTube videos of Kris' Challenge 210.
As you can see by the image below, getting to the cat to replace it with a decat is a laborious task and takes a lot of work. Once the Milltek decat downpipe is installed though, it's 100% worth it.
The image below shows the difference between the stock, restrictive cat, and the Milltek decat downpipe.
Not only is this a modification for performance as you will see via the graph below. But it always makes the F56 sound incredible. With the valve open, the pops and bangs are very obvious with an increased volume and brilliant tone from the 4 cylinder 2.0 engine. This particular model is the automatic gearbox and on up/downshift, sounds amazing. Because the rest of the exhaust system is standard the resonators will prevent any drone on long motorway journeys, as well as having the option for the valve to be opened, closed whenever you wish thanks to the JB4.
Onto tuning. The customer opted for the JB4 for the ability to switch maps, open and close the exhaust valve and the ability to remove it any time. You can see from the graph the power difference is incredible, taking into consideration, the standard test was performed with the decat fitted which usually adds about 10 bhp and 20 ftlb of torque alone, without a tune. With this in mind, the car made perfect standard figures, as expected.
Power gained: 49 bhp
Torque gained: 52 ftlb