You may have clearance issues w/ the rear sway. The NA2 sways generally don't clear one of the cats on an NA1.
That being, said, however, I've have had a rear Zanardi bar on my NA1 with NA1 cats...just mounted it upside down and it clears the NA1 cat (its close, but it clears - and doesn't hit). Works the same, just mounted flipped.