got a magnex too......... and the decat....... if u hav read the thread about my MOT... u might see i am having a few problems with it.
anyway, to be honest i noticed hardly any noise difference with the cat on/off but it pops/gargles alot more with the cat on funnily enough.
BUT when sitting idle, the deeper note comes from the decat, which makes your car sound like a beast sittin at the lights
Marc.