These were run on my sled around an average elev. of 4500ft up to a max around 6500ft in my local area. As for a y-pipe these are twin pipes w/ individual mounting flanges, one for each cylinder.
Back to the top again. Had these sold and deal fell thru. So up for grabs again. And no, these do not physically fit on an 800, the flanges are smaller they otherwise fit in the chassis.