What is a underdrive pully system. I have an 2005 Roush and was wondering if putting one on will do antthing for me. I went to ROUSH parts .com and thay have one and they adives it would inrease HP. ANy info in this would help.

 

Its the pullys that power your alternator and some other junk, Yes they will give you maybe 10 HP. Its a more efficiant pully that slows down the accessorys, like the power steering pump i think. Sorry i sound like an idiot answering it but i dont know much about it but that will help you alittle lol.