Underdrive Pulley on stock TA
#3
overdrive pulley on your alternator due to the lower idle. Head/Cam cars
generally have a high enough idle that the overdrive is not needed.
Gains from UDs on LT1s are a heavily-debated topic.
The LT1 does not use a belt-driven waterpump, so the gains are not as
significant as you might see on other motors.
http://www.ws6.com/mod-2.htm <-- dyno results from pulley install
Would it be my first mod? No... you gain gain a whole lot more from a
cold air intake, a nice 3" catback, EWP and a performance mailorder tune.
Even swapping in an aluminum driveshaft from an LS1 or bypassing the TB coolant passage will net a few HP dirt cheap.