I realized this morning, why not do the math to see what RPM ranges are affected?
NONE of this math takes backpressure into account. Only self and cross scavenging effects.
https://www.musclecardiy.com/performance/exhaust-system-performance-math/
The front pipe length from cylinder to center of GB (or H pipe) is 45 in.
This results in a self-scavenging effect around 4900 rpm.
The rear pipe length from cylinder to center of GB (or H pipe) is 27 in.
This results in a self-scavenging effect around 7900 rpm.
The total pipe length from front cylinder to rear cylinder through GB (or H pipe) is 72 in.
The timing separation between cylinders is 305 deg and 415 deg.
This results in a cross-scavenging effect around 2500 & 3800 rpm.
The stock system is designed for a broad torque band, with tuning at 2500,3800,4900 & 7900.
Removing the GB and putting straight pipes on increases the pipe lengths.
Assuming stock debaffled mufflers (18" long) in stock position (6" from end of stock pipes).
The front pipe length from cylinder to tip is 58 in.
This results in a self-scavenging effect around 3900 rpm.
The rear pipe length from cylinder to tip is 41 in.
This results in a self-scavenging effect around 5200 rpm.
There is no cross-scavenging effect.
Based on this, there should be a good torque peak near 3900-5200 rpm, with losses at 2500 & 7900 rpm.
I would expect the increased flow would offset the 7900 rpm tuning, resulting in a torque loss only at 2500 rpm.
Adding an H-Pipe would probably bring back the stock tuning, plus better airflow and high rpm.
With short straight pipes (stock length) and no H-pipe, the self-scavenging effects occur at 6500 & 11900 rpm.
Not ideal for a cruiser, but should make a great drag bike, if you lengthen the rear pipe out to 27" (7900 rpm).