ofourcobra

i have an 04 cobra vert ,i am wondering if anyone has installed any pullies in there cobra ,i mean i dont want to go with the smallest pully out there but now i am seeing tensioner pullies ,,can any one tell me what the difference is ,,or maybe hook me up with a reputable pully company ,i just want some moderate gains but it seems like everyone is making pullies now a days ,,any help would be great