I had a 50th v8 defender with the centre silencer replaced. As discool stated, crackled and popped on the overrun and generally got on my tits after a while. Felt like one of them boy racers making lots of noise and going nowhere fast because let's face it, a 4 litre rv8 isn't fast.
Replaced it with a cat back Rimmer Bros system which made a lovely burble and not as intrusive and felt quicker too. May have been my imagination. Theoretically the car should lose power with the centre silencer removed, which was why I asked you to make a comparison before and after in your earlier thread