I found it a bit of a pain as it is 2 different diameters. From the manifold end it is 45mm, then It goes to 50mm. I bought a slightly shorter 50mm flexi with clamp ends and a 50 to 45 reducer. I chopped the clamp end down on the flexi and welded the reducer on. I also found it needed a bit of an angle for it to sit nicely.
The old flexi needed chopping out with a reciprocating Saw, which was awkward on your back, but doable.
I had the added complication that the exhaust hanger was rotten too so I had to make a clamp on hanger as well.
I clamped it all on, but it took 2 attempts to seal properly. It was a bit of an arse of a job, but not too bad.
I would be tempted to just get a garage to do it unless you want to do it yourself.
I am half expecting the rest of the exhaust to need changing in the next couple of years, but it's currently looking reasonably solid.
