i have a 13.25 con fe, it is grabby, but i asked many folks before i bought it. it is jumpy backing up a big trailer, so i usally throw it in low range, makes it much smoother. i have right at 400 rwhp and it is fixing to get 50 or so more. i used it in the sled pulls last weekend and it did fine, but i took it easy out the hole[3rd low range]. i have slipped it trying to do a third gear burn out from a dead stop. it was real fresh at the time, might not have seated all the way. i have not tried it again. but southbend has the best all around clutches for our truck imho. mike