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Its been a while since we had a new Mini part to dyno test and tune and this part is well worth the wait. The ALTA JCW Catback (fits Cooper S as well) replaces the entire exhaust system from the downpipe to the back of the car. This means you keep your stock downpipe which is the ONLY downpipe that doesn't throw check engine lights or cause other emissions related problems.


Just like our catback for the other cars, its a 3" 304SS system with dual wall, dual exhaust tips, and includes v-band connections along with one slip fit connection. This provides the ultimate in adjustment as well as a gasket free exhaust system. In fact, the JCW catback consists of all the same parts as the Cooper S part, except we added a new front section that connects to the stock downpipe. This large 3" system provides maximum HP while being very mellow and keeping your neighbors happy.

First off is the car. The car is a 2012 JCW Coupe that has our Front Mounted Intercooler already installed,and stock intake with ALTA panel filter, along with an AccessPORT (duh). We wanted to show case what kinds of HP is gain with no ECU tuning as well as when running a Stage 1 FMIC AccessPORT map. As we have shown in the past with stock ECU tuning, there is a huge variance to HP run to run. Here is a graph showing this. You can see how there is a pattern to what the ECU is doing.


So why does this happen? The stock ECU tuning is very limited in how much extra HP is added. We always find that aftermarket parts only get you so far, then you need a tune to get that extra power. The above graph is the stock mapping on a JCW with only our larger FMIC. Take note of the groupings of TQ and HP. These are actually two separate sets of 7 runs. This pattern is very repeatable. Anyone that shows dyno results for aftermarket parts with the stock ECU tuning, should see this same variable. If this isn't taken into account, you can see how this could completely skew the results.

The below graphs show our catback dyno results on the stock ECU tuning for both of the hot and cold runs. The colder runs made less HP and the hotter runs made more. This was based off coolant temp along with oil temps. We did 7 runs, then swapped out the catback and these were the results.


You can see that on the stock ECU tuning, HP is gain in the 3000-5800 RPM range. In these results you can see about 3-5 Wheel HP. Now we re-installed the stock catback, but flashed the ECU to the Stage 1 FMIC 92 octane map. Because of how we tune the maps, we have no issues with the varying HP run to run. Notice the difference in TQ from stock ECU tune to the AccessPORT tune!


As we expected, more HP was gained with a tune as there was more air flowing through the exhaust and more demand being put on the stock exhaust system. You can see that a solid 8-10 WHP is gained from 5800RPM on up.

The final test is more for fun to prove that our cold air intake does make a difference in all stages of power. We have lots of graphs that show gains on stock cars and tuned cars, but this was a test that we did backwards. We took the 2012 JCW (with ALTA FMIC installed) and installed our ALTA Cold Air Intake, then did some tweaking to the map to get a bit more HP. This made the 241 WHP and 276ft-lbs of TQ you see below on the blue line. We then took the stock air box and installed a new stock filter and dynoed the car again.


Big surprise, it lost HP!!! Of course it will, the stock intake is a restriction, and at this power level you can really see where this comes into play. Almost 20 WHP is lost at 6800, that is very noticeable and for sure going to kill some of the fun in your Mini. This was a great test and one of the first times we went backwards to prove a part.

To wrap it up, 10 or more WHP can be gained on your Mini JCW after installing our ALTA JCW Catback system. Also some really cool new sounds can be added with a nice deep throaty sound coming out the back of your car.

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