Header Noise Reduction

[cycleguy55]

Finally found some information on sizing of crossover pipes:

"Balance pipe sizing seems not to be overly critical. The only really influential dimension is the pipe diameter. This needs to have an area at least equal to that of a 2.25-inch diameter pipe (4 square inches) with 2.5 to 2.75 inches being preferable. Though limited to tests on engines up to a little fewer than 600 hp, there seems to be no measurable benefits to using a crossover pipe bigger than 2.75 inches in diameter. As for the crossover length, dyno results indicate that 18 inches responds in virtually the same manner as 72 inches long."

Read more: Auto Exhaust Science

Based upon that, looks like I'll go with 2.5", assuming my exhaust shop can figure out a way to make it work.