There is no better cable made than the oem cable. If you are having problems, get the firewall adjuster and use ONLY the oem cable, $40 from buyfordracing.com, or mm (they sell oem cables)
Don't care what hp you're running, if you have a street powered stang with a tremec, t5, or gforce, use the oem cable.
you're problem is likely binding caused by bad routing, or other issues. Be sure it is routed UNDER the k member. Poke it down above the steering rack, right near the oil filter, and have it go under the car to the clutch fork.
do NOT use an adjustable cable. I don't care what they want to sell you, if it's not oem, it's not as good.
fyi, if you have headers that are getting in the way and burning your cable, use the sn95 cable, it will route further away from the headers (it's slighltly longer) mm sells the sn95 cable too. Don't buy from a ford dealer, they'll want your first born.