I find it hard to believe in today's performance world that people are using such long pipes on V-twins.
In drag racing where top end is king, pipes for this type of motor will be about 39" to 40" long without baffles. Any longer and the pulsed won't reach back to the heads and block off the out rush of incoming fuel charge and a loss in power will take place.
Now if the cams have been specifically designed for this length, it will help out, but even low end will suffer a lot with this length of pipes.
Also 2 into 1 exhaust increases performance over the entire torque range. But with the M3W it would be a bit difficult to incorporate a 2-1 system.
I remember a guy way back when I was a kid, he and his buddies rode Harley Sportsters. For Halloween one year they dressed up and they mocked up some very long pipes that shot up on the rear about 4 feet. I talked to him later and he said that when they added the extra 5 feet or so of piping he could hardly get out of his own way, it ran sooooo poorly.
Just thought I'd through it out for discussion.
Maybe it's not as important in the M3W.
