I migged by own in some 3 years ago, flexi was £25 from Ebay, a quality bit of kit. its sold with clamps, but thats jusst not my way of doing things, took a bit of trimming with a angle grinder to get it to fit correctly. You also need a 50mm joiner as you need to cut the pipe just after the Cat, and the joiner is there to err 'join' the parts back together. I cut out about 1" of pipe. I also reversed the hanger for the exhaust as even after trimming the flexi the pipe was still a little further rearword that it was originally
Owl job took about 3 hours from memory
been spot on since
Cheers,
Paul