Any reason a transbrake valve body would be slower than non tbrake VB

Chrysler did some testing in the mid-late '70's and found that (all else being equal, including converter specs and overall vehicle weight) a 904 is about .15 faster in the 1/4 mile. I believe this was done with SS cars from that period.

As for the trans brake, I was told that there can be a draw on performance because of the pressures it operates at. But I'm not sure if one is suppose to increase line pressure with a trans-brake and/or if the brake itself creates more pressure/drag by how it operates.