I was thinking to rebuild my T56 tranny: the way it shifts is (usually) a sign of worned synchros... (slow shifts and gear clash).
Because of another reason I removed the belt of my Vortech SC and noticed how good and fast I was able to shift

I think there is a residual pressure between the blower and the throttle body: this "pushes" some air in the engine and doens't allow it to reduce the RPM.
This could be caused by a too small bypass valve, but right now I don't want to modify the system

This is a mechanical throttle body with an idle pintle: is there a way to reduce RPM during shifts modifying the program? Like reducing timing? Or cutting off the fuel?

Another thing I noticed: the F-bodies (like mine) have the idle set at 800 rpm. It is 800 when the car doesn't move, but when I drive (no gas) and push the clutch the engine speed doesn't drop below 1000 rpm. Why? This is not a clutch issue, it's something in the program. Is there a reason? How can I modify that using LS1Edit?

Thanks - Stefano

I find out that Idle Air, Airflow Decady in Gear and Throttle Cracker Airflow influences the engine speed between the shifts (when I let off the gas pedal).

With different settings it is possible to close the idle pintle completely: this avoids residual pressure to enter the manifold, what (in my case) caused too high RPM while shifting.

To me that is the whole purpose of a popoff / release valve when using boost.
I have seen cases where 2 popoffs are required or the size if only using one

I doubt shutting off bypass air via IAC would make that much of a difference.

I have the standard Bosch bypass valve supplied in th Vortech kit. I was considering an adjustable valve like the Maxflow (also supplied by Vortech).

Mine is the 6 PSI kit and I was thining the Bosch valve was good enough... but maybe not.
What valve would you suggest?

Before chenging the tables I mentionned I had about 15-20 G/sec while shifting (gas off).
Now it's around 10-12 and it actually shifts better

In the original F-Body program the air values are about 3 times higher than for the Corvette of the same year. I loaded the Corvette tables, included idle.

In almost all issues I have seen with decel and/or idle issues and having boost is either the popff is too small, not installed properly or requires 2 popffs.
Some popoffs only require changing the strength of the spring in it.