I have fitted universal mufflers to my VRSCR, along with a K&N filter and PCIII.
I have had several dyno runs done and HP now up to 118 at the wheel, with a custom map.

However, after running for 3 weeks i have a LARGE amount of soot forming on discs and blowing out, which obviuosley indicates it is running too rich. Having spoken to the technician that dyno'd the bike, he tells me he is not surprised as he is unable to get the O2 sensor in the exhaust system with discs and end cap on. He mapped the PCIII using the O2 sensor then refitted 10 discs and end cap.

I am now having running issues, believe spark plugs getting fouled (which i am about to check).

How are the dyno guys meant to be able to custom map my bike, using these mufflers if they cannot get O2 sensor into the exhaust system? I know i could add more discs, but i do not want the extra noise.