hello, new to this forum, Ihave a 03 mcs and recently installed a craven 15% supercharger pulley on it. managed to snag a exceptional deal on the pulley on ebay, usually I get beat out the last minute on things, but as they say,every dog has his day.... I sure this subject has been covered before, so excuse this newbee for asking. for those with 15% pulleys, how much in terms of miles per gallon did you loose. I understand that suddenly after installing said pulley gennerally we have our foot in more often to 'test' it out. Did notice smoother acceleration with the smaller pulley, and the fun to drive factor has increased at least 25% by my estimation. The on board computer shows my milage went from 27.3 avg. to 23.4 since the pulley was installed. still worth the milage drop for the performance gain, so I'm not complaining!

 

This answer has to do with YOU not the pulley. Even though I wish it was an ALTA pulley on the car, no matter :-)

The pulley will lean things, out so you will get BETTER fuel economy assuming you can keep your foot out of it. So depending on how you drive is going to determine the fuel economy.

Hope that helps and ENJOY the new power! Best mod for the car, hands down!

 

Did the ALTA 15% pulley about 2 months ago, then a M7 thermostat, great way to go from 35 highway 28 mixed down to 23.0 highway 23.3 mixed