Here at Promini we get this question every day. On a Supercharged or Turbo charged vehicle you need only to increase the boost, along with decreasing the exhaust back pressure, and horsepower will climb very quickly by as much as 35%. Keep in mind as you increase power beyond 200 H.P. fuel mixture must be regulated very precisely. Fortunately the Cooper "S" fuel programing from the factory is somewhat rich. This allows us to do some very ipressive performance modifications without having to modify the fuel mixture. Choosing which modifications to do first is very simple. Air Intake, Performance Pulley, Exhaust System, Tuning Software. READ FULL ARTICLE - How To Improve MINI Cooper Performance
Cooper "S" intake system:
The most popular and biggest bang for your Buck is a PROMINI free flow "Racing Filter Kit". This modification can be performed by the average car enthusiast in about 30 minutes. The end result will be a gain of approximately 10 to 12 H.P. The magic behind this upgrade is simple. The less restriction to the supercharger on inlet side, the more the supercharger can compress the air on the engine side. The result is a boost increase of 1.5 P.S.I. The Dyno result is an increase of approximately 12.5 H.P. The results are plain and simple and the Dyno Chart will show you the results. For more info click here.
Cooper "S" Supercharger Pulley
20 H.P. for only $139.95 Smaller Supercharger pulley: The magic here is real simple. Reducing the size of the Supercharger pulley increases the Supercharger R.P.M. End result, the faster you turn the Blower, the more you increase the boost. PROMINI offers pulley's in three upgrade sizes 15%, 17%, 19%. Our pulleys are C.N.C. machined collet style pulleys, they do not require a press fit. All three require the same install time. Naturally the 19% pulley offers the highest H.P. and torque improvement. Expect a 20 H.P. gain.
Installation is recommended to be performed by a professional. Allow approximately 3.5 hours installation time. For more info click here.
Cooper "S" Performance Exhaust System
This area is easy to over look, once you have done both of the above. However you need to keep in mind, that the more air you put in the engine, the more exhaust that needs to escape. This increase in exhaust volume also increases back pressure and heat. Adding a Free flow Supersprint exhaust system will allow you to maximize your performance gains. The great feature with a Supersprint system is that you have the option to add the larger diameter connecting pipe at any time. If at some point in time you decide to increase performance to over 225 H.P. Another big advantage is the Supersprint street system has a deep sporty sound without violating any sound emission requirements.For more info click here.