Hey I was wondering if installing a lightweight pully kit or just the underdrive pulley makes a difference?

Do you think that it would be a bad choice to go with ebay ones?

 

like always, ebay is not a performance parts store, and sure lightweight pulleys will help, it all apart of the whole idea of losing rotating mass, so sure if you've got that lightweight flywheel and if you get lightweight pulley's it all helps

 

Also with underrive pulleys you'll have to worry about you accessories not producing enough power. Hear some cases where the A/C was not blowing cold enough or the headlights being dim becasuethe Alternator isnot producing enough power.