We'll skip that explanation then. I think there's enough in this thread, that when put all together would explain my reasons. Most of them, anyway.
Here's a very interesting case in point about the importance of straightening out your tuneup before you go changing TCs around. I don't know why I didn't think of this particular case when we were in the heart of the discussion, but this actually occurred within the last 6 months.
A customer of mine, who I had built an engine for, but not tuned, called me up a few weeks or so after taking delivery wondering what stall TC I had supplied to him years previously. We had also done the trans for him many years previously. I told him I couldn't remember exactly, and asked what the problem was. He told me he had someone helping him tune the engine and they felt the stall was too low for the combination. I believe they were experiencing a stall speed of around 2200 rpm, where they were hoping for 3200. The exact numbers I don't recall, but you can get the picture that the stall was way off from what the customer was hoping for. I asked about some of the tuning parameters they were using and how they were testing the stall speed, and I got the impression from the answer they gave me that they really hadn't gotten deep into the tuneup yet and were actually a little lost. I asked them how they could judge the TC when they really hadn't done much with the tuneup yet. The answer was something like, what? The customer ended up bringing the car to me to tune.
When I had finished with a very safe tuneup, the TC was stalling at or above what the customer had originally been looking for. This was accomplished without changing the torque converter.
If the customer had jumped the gun and changed out the torque converter before he realized the full potential of his new engine, he would have wasted his money and would have ended up having to put the original TC back in after the new TC was found to be too loose with the finalized tuneup.
It was amazing that a tuneup actually made that much of a difference, but it did. Even I was surprised.