My advice is get an exhaust that is made to fit your car, rather than a universal one that you have to make fit.
Universal ones will touch in the wrong place and need different mounting points adding, either to the car, or to the silencer... Etc.
If you search for "Custom Stainless Exhaust" you will find a few places that make them - Powerflow, Longlife, MIJ in Rochdale .. in stainless steel at not much more money than a ready made one.
If you want to go the route of getting something and then making it fit.. measure the inlet and pipe diameter on the mid-section and on the back box.. then get an adaptor made up to sleeve one to the other.. E.g. 54mm to 70mm You can get these on fleabay .. but make sure you know the length you want.
Then.. get an angle grinder. The old back box doesn't want to be recycled so it'll be a bastard to remove.. or the exhaust could be one piece. You'll need to amputate it.
Once you have the mid-section separated from the back box, measure it all up.. get an adaptor and then fit it all together. You may need to trim the stub into the new back-box to get the overall length how you wants it.
So.. angle grinder and some jointing putty is all you need.. but as above, check the back box physically fits under the car without jamming the suspension or rattling the body.. and that you can mount it properly (i.e. not with a very long cable tie).
Ralf S.
