I recently purchased a 2004 Monte Carlo SS Intimidator with the supercharged 3.8. I have been reading through this forum and another MC forum and everyone suggest changing out the sc pulley for one with a smaller diameter (and the belt too) for more horsepower. From what I understand, if I get the SLP pulley kit from summit or another site I will gain roughly 25hp BUT how much gas mileage will I lose? Has anyone done this upgrade and noticed a drop in mileage? I ask because this is my first car with a supercharger so I am not familiar with how changing a pulley would affect the mileage.

I am also going to change the intake (or gut my current one) and get the ubend delete pipe too. Besides that I see no reason to change anything else on the car.

Thanks for any info!!!!

I can't speak from experience but I would imagine your mileage wouldn't change much, unless you were hard on the accelerator all the time.

smaller pulley= faster boost pressure build up.

Mileage will be minimal to none in change, where is this MC forum? We have an 04 monte SS and id like to get a new intake and exhaust, retune the computer then start on internals once the warranty is up.

I think I am not going to change it out. Many of the mechanics in the are are telling me that it does increase HP without hurting mileage too much BUT it puts a hurtin on your engine and wears it out quicker.

I think I am not going to change it out. Many of the mechanics in the are are telling me that it does increase HP without hurting mileage too much BUT it puts a hurtin on your engine and wears it out quicker.
The Mechanic you consult is a moron. It wont hurt anything on the engine, you have more then enough fuel Pressure and air going into the motor that a psi increase coming from the blower wont hurt the motor. You will be fine and so will your car.

Not trying to argue with you but I had three seperate mechanics tell me almost the same thing. I will admit that one might have been slightly retarded but the other two only work on performance vehicles and are damn good at it.