I would like to remove my old backbox but it has been on for so long, it just wont come off, iv removed the exhaust clamp and tried everything to pull it off and chisel the backbox off but no luck, its definately not welded on

 

Hacksaw mate, then buy a sleeve to mate the new one up

 

was hoping i could get it off without sawing but looks like i might have too

 

Heat it up?

 

Use a grinder to cut through the outer pipe only, basically extend the slots in the back box

 

do this^^^^

 

spray with WD40 leave for 30 min put a heat torch on it for a few mins then it will twist off