It sure seems that way. I have my stock pipes down to the front baffle and the one behind it. I drilled 3 additional 1/4" holes in the front baffle, and an extra 3/4" hole saw hole in the 2nd baffle*. Mine has no catalytic screens. The sound is a bit loud yet rich, but not gutted Harley loud. I can still keep it quiet, yet bark off the line if I want to.
The bike seemed to come alive by widening the exhaust smoke escape route. In that I live in a rural area with relatively little traffic, I often ride by ear, (all things considered) yet with enough RPM to be sure I'm not lugging. Prior to the drilling, the mid 3,000s seemed to sound right. Even though it's now louder, the engine seems to want to run in that 4,000 RPM sweet spot I've read about in here.
I tanked up yesterday in the morning, and then again last night around 10 pm. 143 miles at 3.02 gallons = 47.35 MPG. In 11,000 miles of a wide variety of road types, I've never come close to that figure. 42 MPG was my prior best. While I'll be the first to agree that one run on a sketchy trip odometer does not an MPG evaluation make, I do have to wonder if the pipes and running near 4,000 most of the time are the key factors.
*If I had it to do over, I may have opted to go 3/4" hole on the front baffle, and the 3, maybe 4 1/4" holes in the 2nd, to allow the greater restriction in between the two baffles, and further away from the air pump / exhaust cycle duty the pistons must perform. Anyway, there probably isn't a huge difference.
