I have a guy with brand new set of lt1 underdrive pulleys he wants to sell me.Does hypertech still make them can't seem to find them on their site and are they bolt on type or do they replace the balancer like the better asp pulley does.I was planning on asp balancer one as had the cheaper asp bolt on and think they added vibration into my last lt1.Also think an auto car needs an overdrive alt pulley and think asp makes one but not sure figure the hypertech one was underdrive alt that comes with the set..
Anyone know anything about the hypertech one ,opinions..

 

Unless you are gettin a killer price on them I wouldn't even spend the money. I think that somebody dyno'd them and they gave an average of 2 hp gain.

You don't have to have an overdrive alt. pulley for the auto...I had one on my v6 and actually had to go back to the stock pulley. As far as I know all pullies are piggyback systems that just bolt onto the stock balancer. I thought Hypertech stopped makin there pullies, but I could be wrong. Anyways, good luck either which way.