I bet you almost anything you were bleeding pressure off somewhere else then or they sent you the wrong sized shims. Either that or you installed them wrong and trust me, many people have done that (myself included!).
If the proper sized shims are used and installed correctly, the shift is obnoxiously hard.
Honestly, this is one of my beefs with the Intense/ ZZP kits. I'm of the opinion that the strongest setting shouldn't even be offered because it has a tendency to put extra stress on the input shaft, especially when combined with a PCM that has increased line pressure. It's reasons like this you need to be a little cautious when shopping with Intense. Their website is (IMO) a freezeframe of how people used to do things in 2004, right down to the limited slip differentials.