The 3rd gen uses the rear lower motor mount bolt for the exhaust hanger so the 2G rear hanger wont match up. You can either make a small bracket to connect to the 2g hanger, or not use it at all. Other than that, it slaps right on. In a pinch, we put a 2g Yoshi full system on a 2018 SV650 at VIR during the Moto America round. no clearance issues.. I would assume the 3g exhaust would fit on the 2g but the exh hanger might have to be modified or removed.
This is all I know: https://www.ebay.com/itm/ARROW-HEAD...h=item2aa2551748:g:siUAAOSwdXdansN6:rk:1:pf:0
I just remembered that Dale Walker has been testing that header for over a year now. He uses that header with his holeshot slip on. He would know.
Reply from Dale: "I would just buy a M4 if they make one for your SV. I cant get Arrow any longer at this time. To be honest the stock header on the early bikes was pretty good, with thin wall tubes and no cat to choke it up."