I started build 4L80E with TransGo 4L80E-3 kit which is very similar to HD-2 but offers full manual control and pressure regulated with vacuum modulator.

I've been doing some research and found a lot of info about 4L80E mods, especially in this thread https://ls1tech.com/forums/automatic...ansgo-hd2.html

After reading that I was convincied to not install pressure relief valve and do internal dual feed of direct clutch. I tried TransGo sandwich plate in TH400 behind 496 BBC and effects were average so I decided to "modify" TG instructions for 4L80E.

But kit instructions want me to drill two holes: first in the LO passage of VB, second in actuator feed passage.



I've figured out that hole in actuator feed is needed to have full manual control of the transmission but not 100% sure. I have no idea what is the reason of drilling hole in LO passage. I don't like just follow the instructions, especially when I know about some issues with these kits.

Anyone know what is the purpose of these two holes?

Thanks!