This is just an FYI since I see the "back pressure" thing alot.
Any back pressure at an exhaust port is bad.
It is a myth from a misunderstanding of how exhaust systems are "tuned" for an engine.
Multi-cylinder exhaust systems work by velocity, which if done right, lowers the pressure at the un-open exhaust ports.
When exhaust valve opens the exhaust volume is push into the header pipe, this creates a velocity in that pipe, when it gets to the collector(larger pipe) the velocity lowers the pressure in the unused pipes.
Where the "back pressure" confusion came from was when some one decided "if a 1.5" pipe is good a 2" pipe must be better".
So they tried it, and lost power???? WTF!!!!
Oh.............the engine must need "back pressure" from the smaller pipe to work better........I am a genius
Oops, not a genius, wrong cause and effect.
What the 2" pipe did was to reduce the velocity and as a result it increased the pressure at the exhaust ports, so larger pipe caused "back pressure".
The size of the header pipe needs to be correct for the volume of the cylinder, a size to keep velocity high which then keeps pressure at the exhaust ports low.
Actual exhaust design is above my pay grade, lol, there are pulse counts and numerous other factors that occur at different RPMs.
But one thing I know, back pressure is bad, ask any one with a clogged Cat.
Long straight pipes wouldn't hurt rings, bad or limited oil supply will cause excessive wear, running rich washes oil off cylinder walls, gritty carbon build up causes sandpaper effect, lots of things cause rings to wear out early.