No personal experience, but here are two member comments from JeepForum:
"the transgo shift kit isn't a performance mod like you're thinking in terms of muscle cars. its more of a fix to correct problems associated with the 42RLE and is supposed to make it shift more smoothly, vs that feeling where the 42RLE doesn't know what gear or lock/unlock state it wants. it requires dropping the throttle body and drilling some holes, and placing a little ball bearing and some springs."
"I've installed the Transgo kit in my wife's 03. It's involved and messy but not too bad. The instructions are a bit of a joke - more sales pitch than directions, but it was sufficient to get the work done. Also, you don't use all the parts which can further the confusion. What you fix depends on your sypmtons.
Definitely a repair kit, not a performance kit like the Transgo in my LX 5.0.
My wife's TJ had the frequent limp mode issue and the kit did correct it."
FYI