http://thunderracing.com/catalog/?ac...vid=3&pcid=111

That should give you some good info. With ASP you could actually get a bigger(overdrive) pulley(which would actually make it somewhat less than 25% underdrive) to keep alternator charges "near stock levels" Most just keep stock pulley, though. I never noticed ANY light dimming, etc..A good mod IMO. Definitely not SOTP, though. A good time to do it is when and if you do a cam swap. You have to take the crank pulley off anyway, so most shops won't charge you any added labor.

btw Teke had to answer all these questions for me when I first got my LS1. What's happenin bro?

 

The UD pulleys are fine for your car and there's no reason not to get them (except for price). They are worth around 8 rwhp and cause NO adverse effects on your car unless your idle RPM is turned WAY down to make a small cam sound larger or something stupid like that.

Mike

 

As mentioned, we typically see 7-9 rear wheel HP with ASP underdrive pulley installs. Power steering/AC etc all work fine with no noticeable loss in performance. The alternator will not charge very well at idle speeds (especially in automatic equipped cars) but as soon as you start moving, everything is fine.

With that being said, the only time we don't recommend underdrive pulleys is if you spend a lot of time stuck in traffic or have a high output stereo system and like to sit in parking lots etc and listen to it.

 

I gained about 1.5mph and lost .2 after an ASP install. However, my Z06 only weighs 3300 with me in it .

Ryan

 

anyone else notice that the thread was 2 years old? Someone just decided to respond to it recently...

 

What difference does that make?? Not new and shiney any more??

We ask people to use the search feature and when they do, old threads are often brought to the top again. Nothing wrong with that.

 

I've had the ASP pulley on since 2001 with no problems. I got it (barely) used with the belts for under $200. Totally worth it IMO...