The non HO 800 y pipes will all (07-09) will all bolt on. You can even take an HO y pipe and take a uni-bit step drill to the 8 flange holes about 2-3 sizes bigger and it will bolt on and line up beautifully. Been running one for 5 years...works very well,
It will work. Most of the aftermarket Y pipes are now notched to work with both motors. If you have a stock y pipe form the non-HO to the HO, it won't fit, but you can oval out the stud holes a bit to get it to line up.