So we have two things that mess with our shift firmness: a PCM, and a shift kit.

PCM's cause firmer shifts by raising line pressure.
Shift kits cause firmer shifts mechanically, by installing a shift kit.

We've heard that firmer shifts are better for your transmission because it reduces slipping, however, doesn't that result in more stress on other parts?
I'm trying to find out the threshold of safety... when is firm too firm?

Shift kits often say right on them to use a low/mild setting if you use a PCM as well, otherwise it may result in broken shafts. Obviously even they admit firmness has a bad spot.
So, are there more transmission problems from broken shafts, or from firmer shifts.

I would like a shift firmer than my intense (soon to be dhp power tuner) is giving me. One of my ideas is when I get the power tuner, also get a shift kit, and don't have that much of an increase in line pressure.
Then we have the question: whats better for transmission life? higher line pressure of the shift kit?
Just sort of toughts/questions rambled into one post...

Bill

Not sure.
After installing my IPCM, all thoughts of a shift kit went out the window. I have been pleased with the firm shifts given by my IPCM.

zuul, if what you say is correct about broken shafts, then I guess the answer to your question is:

Would you rather have to replace a broken shaft (too firm), or replace the clutch packs (stock)?

Neither one sounds appealing to me, so I think you just look for the middle ground.