I have a 92 RS 5.0 t-5...I alos have a $25 credit ihave to use from summit bu the end of the month and was thinking of getting a set of under drive pulleys...motorvation i believe..but before i spring for them i was wondering what gains or loses to expect...thanks

 

I don't think they're worth it.

They just lower the speed you turn other accessories, so for example, slow down the speed you spin your water pump, drawback is less cooling, but since you're using less power spinning it, you gain a few HP. Usually they're mild enough not to slow down your accessories to the point you notice, and then of course don't give much power.
I'd say save that for when you've max out the power of the engine, and you're looking to squeeze the last tiny bit of efficiency out of it. Best used on a new honda or something that's already at top efficiency. I think there's better ways to get power out of your engine.

 

I put ud pulley on my Z and "think" it made a difference, but I've never run my car on a track to check times so if it really did or not I can't say for sure. I just did it as part of the standard bolt-on goodies like cat-back, supercoil, K&N's, open up plug gap, etc.

One thing I can say is if you cruise around town at night (lights on, maybe A/C on, etc) I would think twice because of the alternator running slower puts out less charge. I had problems with this so I put on a smaller alternator pulley and that helped some. Still, the battery charge will start to drop if doing much stoplight-to-stoplight driving.

Also, I'm on the second alternator (and it's now making noise too) and I think it's because of the heavy charging it's trying to do at the lower RPM driving around town. These are "quality" alternators - GM original and GM reman. Yeah, two alts doesn't sound too bad at first, but the car has only 35K miles....

 

I bought the BBK underdrive pulleys for my setup. Of course, I had no other choise, I have no other pulleys to put on. I've heard yes and no's, if you just want to have something to do on your car, then get em. Take it to dyno and let us know!

Only $120, $95 with your credit.

If your saving (seriously) for a power adder, might want to hold out on the pulleys and get some chrome BLING BLING!