Factory exhaust does not seem to allow for oil filter removal

I could not get the oil filter, plate and bolt off for a service unless I lowered the standard collector box by loosening the header pipes and releasing the two rear collector box mounting bolts..
Considered de-mounting number 3 header pipe from cylinder head and collector box instead but it did not look like it would make enough room.
I do not have the Z1-R Kawa Service Manual - but is this really how you are supposed to do it. Didn't seem to be enough clearance any other way.
Any advice or tips for next time appreciated.
From Mark