Sorry to bring up this old thread again, but wanted to add some comments on the performance of these mods.
First JWT is right on with the compressor mods increasing the tendancy to cause barking when letting go of the throttle. It happens only in extreme cases but it never did that before the mod.

The waste gate mod is still in limbo as far as its gains. I set it up to do a drive pressure measurement and then I had the electrical problem I have today. Just now getting back to messing with the truck again and trying to get it fixed.

I will measure the drive / boost pressures after it is back up. At the time of this mod, I was having the engine fire ringed and set up for higher drive pressure, boost and increased exhaust flows. Interesting comment that opening the gate further would increase the negative delta P. (I am not doubting the comment at all, as this is a hobby for me and not my profession). My thought on the mod is that it would cause the lower turbo to spool up more and move more air into the upper turbo. My assumption of drive pressure was based on that I would reduce the DP across the upper turbo turbine and move it to the lower turbo which has a bigger turbine nozzle and result in a lower drive pressure for a given exhaust flow. I assumed that the lower turbo had some room, but in honest I was guessing were it was operating on the turbo map I had. I understand that "assume" is an accronym.

As far as egt's in real world with the mod:
Even with HRVP and Mach6 I rarely could get it over 1250F. In other words, the fear of death set in before I was worried about egt's... They don't drive like a BMW M5....

I certainly didn't loose anything obvious by doing it. It pegs my 60 psi guage very quickly and doesn't seem to have lost its spool up. I have not yet run the comp at any high levels since I wrap the rear springs without a tracbar on 3x3.