Does this the centre section on this exhaust replace the resonator & the cat, or just the resonator?

Also, anyone know the cheapest place to get a green panel filter. All for MY05 Sti.

Cheers.

 

Both

 

with the nur spec r u get 2 sections, the back box and the centre section, the centre section has a resonator box in it, takes out the middle cat from ur existing exhaust and the cat in downpipe remains great exhaust