Underdrive Pulley Thoughts?
 

I have a 1994 Mustang Gt and i was thinking of getting a BBK underdrive pulley Kit for my car and was wondering if it would make a noticable difference in my cars performance?

You won't see or feel any noticeable difference IMO. If you add up several of these small cheap mods, where the total = 20+ HP gain, you will see and feel a change.

You will notice if you've got a stock alt, that your lights will dim when your stang is sitting and idling at night. We upgraded our alt to a 3G 140A unit, no problem now.

Isnt underdriving a larger alternator basically cancelling out the underdrive pulley's purpose? Just wondering cause I could use some extra juice to run all this stereo equiptment but my UD pulleys keep the ammeter needle dangeously low at night with the lights on and my stereo going.

Well on my car my best before the pulleys was 13.62@99, put on the pulleys an went a best of 13.33@101.

No charging or cooling problems.

i agree that some people like them and some don't bother.. I wouldn't bother, on a stcok car not with it and you will have the charging problem at your door.. The upgraded alternator is best, but for the cost your going to spend its not worth it. A cold air intake or TB upgrade would be better or headers.. Headers are #1 upgrade for power.

i got a set of march underdrives. not a huge gain, but i did feel a LITTLE something. i also have a pa performance alt. although the stock voltage gauge drops a decent amount with lights on and sitting on the brake pedal, no charging issues. the UD's work by providing the alt with a smaller pulley, thus turning it less and robbing the the engine of less power. the pulley that came with the pa performance alt was smaller than stock, and the march UD pulley was even smaller. march also makes a "power and amp" kit which comes with a larger alt pulley. if your really concerned about charging and dont want to spend the dough on an alt, buy the UD kit but use the stock alt pulley and your should be fine. if a UD kit gives u 10 rear HP, leaving on the stock alt pulley will give u 9. u can even buy a bigger pulley for more charging

I also have the March underdrive pulleys and did notice a difference after I put them in. Its not huge by any means but was worth the money. As far as charging goes.....that all depends on how big a stereo you have or the amount of accessories you are running. Some people keep their stock pulley on the alternator to help out with charging.