The weight is surprising!
The Indy -3 is 22 lbs w/ valley plate.
The Indy -4 is 25 lbs w/ valley plate
The Barton is 35 lbs and has a built in valley plate. The thing is an anchor, but it makes power.

All I've tested (naturally aspirated) are these three 4500 flange manifolds. On my 572, the Barton is the best of both worlds. At least 1.5 tenths quicker and 2 mph faster than the -3.
The -4 is faster on the backhalf, but lost a lot of lowend grunt...1/2 a tenth slower in the 60' compared to the Barton. The big -4 needs to turn more RPM to shine...my combo is a little too mild NA to utilize it.

I'm putting the Indy -4 back on it soon since it's pretty much only gonna be run on nitrous from now on.