Originally Posted by Rucksta
Conventional wisdom says the cross over increases efficency by allowing the cylinders to share the mufflers, increasing the muffler volume available to each cylinder.
Why are you adding a crossover to a single muffler design?
Am I misunderstanding your use of "cross over" and you mean the same as junction box or "Y" pipe?
It also allows the cylinders to share the volume of both headers. Just because a bike has a single muffler doesn't mean that the crossover won't have any effect. BMW put crossovers on both the R100GS and R100R - both single muffler models.