How to replace cat with resonator

[Aleman]

What do I need to install a resonator in place of my rusted and busted cat? To a relative noob without welding equipment, it's not too obvious. I've got a fairly new muffler on my '90 325is, so I'm not ready to replace that just yet...

I'd like to put this single inlet/outlet resonator:


In place of this two inlet/outlet cat(please ignore the blue & green markings in the pic):


Thanks for any advice!

[CW325]

You would need some extra pipe welded in where the down pipes are and you would need two Y pipes. One before the resonator and one after.

[e30slidewayz]

Any shotty muffler shop should be able to do it. Shouldn't cost more than a bill.