i think and obvious point has been missed here.regardless
of what a dyno says,you dont ride it standing still.if
a pipe made exactly the same power and weigh 35lbs
less,thats effectively adding 5ft/lbs of torque
everywhere to the bikes power.thats like dropping
a tooth in the front sprocket,thats significant.normally a breathing
mod will lose somewhere but gain elsewhere,bigger primaries
tend to hurt part throttle torque compared to stock headers but although you often
ride from 2-50% throttle position,your dyno sheet
shows at 100% throttle,everything is rosy.timing and fuel trimming
can help but a smaller pipe will always scavenge
better at lower throttle percentages and or rpms,than
a larger pipe.