Well, the JZA80 and JZZ30 share the same style cat, but the length of the DP is different and i think the bolt pattern for the 2jz differs from the 1jz. The JZA70 has a completely different type of downpipe that extends under the car where the JZA80 and JZZ30 ones stop. Thats on the J-spec models though, not sure about american MKIV supras