Super Charged and Turbo Charged MINI engines can benefit with having the intake manifold ported to increase CFM and better improve cylinder air distribution. While this may seem a simple enough modification there are numerous methods of properly achieving the highest level of performance increases. As well every engine variation will have different end results as far as levels of power gains which cannot be compared from one engine to another subjectively. Intake Porting can be the basic manifold plenum and runner clean up to highly extensive port airflow reconfiguration for balancing cylinder to cylinder load for the adjusted least amount of fuel correction. That is one of the challenges to the porting specialist with regards to the single plenum x4 runner intake manifold used on the MINI. The two farthest cylinders will never get the same air velocity as the ones closer to the air supply or Throttle Body. Many shops offer intake manifold porting which will clean up the casting by removing undesirable material that could potentially slow down or disturb the air flow. Also the evenly removal of interior plenum and runner areas will increase the total CFM or air that can be pulled though an engine if naturally aspirated or pushed through the engine under boost using a Super Charger or Turbo Charged unit. These shops are experienced enough to know not to remove too much material that without considerations such as other engine parts and the end use of the engine could cause less than anticipated or diminishing results. It is possible to actually remove too much material in some areas and cause a loss rather than gain in power. This is one very good reason to have someone experienced in manifold porting perform the work. The end results of basic intake manifold port work will increase both your torque and Horsepower. For some that may request specific percentage or Dyno result numbers showing exact TQ and HP to use a basic rule of thumb to go by there really is none. As mentioned earlier there are too many variables to consider for any standard of comparisons. The end results of HP and TQ increases is the reward of how much custom porting and flow bench analysis testing to your individual engine and components is done. This kind of custom port modifying will run into considerably more money than basic offered manifold porting. As always a good practice after any engine performance part installed or modified is to have the MINIs ECU mapping adjusted which will always help add to the increase performance level safety and reliability of your engine. For more information I recommend contacting a local Performance Engine Machine Shop experienced in manifold porting in your area or one of the MA vendors that offer this type of intake manifold porting.