Originally Posted by Ol'Muley
Have you checked @ factory early 2000s sm or sc should have mid pipe call Chip Munn @ munnracing .com
I just placed an order with Chip for some parts yesterday, didn't even think about asking at the time but I'll give him a call.
Originally Posted by juames
From what I'm told the pre-silencer doesn't affect air flow, so leave it on...unless you are trying to save a few ounces of weight.
I've been speaking with Derek at Motolab, he's done a lot of dyno work with different configurations on the 640 and suggested the non-mufflerized pipe. It's not so much about power but instead is about heat management.
Originally Posted by bmwktmbill
Had the replacement on my '02 640a for years.
It smoothed out the power and a seemed to have a few fewer vibes.
Coupled with the Comp muffler the BST40 pulls flawlessly from Zed to redline.
And runs great above the treeline.
It's how it wants to be.
Any idea if theses are still available anywhere Bill?