Cat solution?

I've been trying to work out a solution to this catalytic converter on bec problem. Is there anything to stop me stripping down my MK Indy silencer, cutting down the length of the silencer internals, fitting a piece of catalytic converter material into the space created at the header pipe end of the can and reassembling the whole thing so that the silencer effectively has a cat in it at the header end? Does there need to be a gap between the cat and the silencer?

Any thoughts anyone.

I think various companies - including maybe MK - will hire out cats for SVA, if that's what you are after.

Mk will hire out a cat its £50 per week + £150 deposit. + Postage
Which is what made me look into making my own!