I had a transgo in my car and did a ton of research after I fried my tranny. Alot of the components and steps that the transgo kit tells you to do will take many miles off the life of your tranny. Also one of the leading tranny builders (
http://www.cahallperformancetransmissions.com/ talk to Frank he will tell you the same) for solid strickly racing version 700R4's and 4L60E's told me the kit is a major factor in most of the core trannys he see's coming in failing.
Believe me, I was a diehard Transgo recommender too but after talking with alot of guys who build auto tranny's to hold up to major power, they tell me the kits are not worth the hassle they cause.