My gut says…it depends. :p
If you want high RPM horsepower, my bet is the 6.1 intake will out perform the 6.4 intake with the SRV locked out. The reason I think this is because (as I understand it) the lock out locks the intake in long runner mode.
If you want low end torque, I think the 6.4 with an SRV lock out will be better. For the same reason.
There’s my uneducated guesses. Take them for what they are worth.
