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

Trying to account for as many variables in the new combo as i can.
When i had the stock stroke 360, car ran a best of 11.26. 727 trans, 4500 8 inch vert
After a time, i swapped out the 727 for a 904 with transbrake, and new 8 inch vert. About 5k flash
The car immediately picked up almost a tenth in 60 foot, but further down the track i went, it gave that gain back. To the point to where the best it ever ran after the swap was 11.33.
Obviously i never saw the 1.5 tenth gain i was hoping to see.
Either i missed on the vert( better 60, but too loose on the big end) or something about a brake valve body( i have always footed it, have yet to use the brake) draws power...
Gonna be curious to see if the stroker with lots more torque likes this vert.