A little bend works for most, otherwise we just cut the pipe off at the cat, cut in a new angle, and re-weld the cat where we want it like we did on the Slugo.
The pipes cat input is not in it's center.
We just whacked the cat off the pipe where the original weld was, put the pipe back on the bike, then just cut the end of the pipe to the angle to match up to the cat with it's thin side to the frame, threw a tack weld on to hold in perfect position to fit nice, and then took it off and welded and painted it to be a better fit.
A press wouldn't help that problem, the cat body was in the way as it was meant for a left side output.
No biggie with an angle grinder with good cutting blade, welder, and good high temp paint though ;-}