And if you are talking 03/04 cobras, you definitely don't want any under drive pulleys especially ones that slow down the water pump.
The only under drive pulley that 03/04 guys install is one for the alternator when they install overdrive lower pulleys greater than 2 pounds because it will spin the alternator too fast and burn it up. I will be getting the alt pulley when I put on my 6 pound lower after christmas.
"When I know more, I'll be forthcoming. Or I won't be forthcoming, and I'll be honestly deceptive." - Les Miles