Need help on exhaust!!

[nissan240sx31]

Im thinking about buying an Apexi N1 Evolution full catback exhaust for my s14. Im buying it off ebay and the guy told me that this exhaust will bolt on to my KA motor but because this was made for an SR20 motor, the piping will be too big for my downpipe and I may have to modifiy the piping or downpipe to accept the 3" piping. What do I have to do or need to fix that?

[80watthamster]

My N1 Dual bolted right up to my stock S13. If yours doesn't, take it and the new cat you have (you do have one, right?) to a shop and have them weld on the proper sized flanges. Or you can obviously do it yourself if you know how to weld.