Anyone know how hard cats are to install? Am thinking (when the time comes) of getting my engine reconditioned and going for an 05/55 plate. But as I understand it if I went that route it would have to have a cat.

piece of p155. insrtalled a cat in my exhaust before the silencer cost me £95. Simply sleeved the manifold / cat joints sealed with exhaust firebond and clamped together. Has the benefit of being removable post test which makes a hell of a difference to engine bretahing. Lambda sensor boss in manifold cost £5.
Let me know if you want any more info.