Want to explain how having a better sounding exhaust isn't a pro?
Or maybe give some evidence to prove that any of the cons are actually noticeable and not just theoretical BS?
Because it's a ******* exhaust leak! You cannot genuinely need explaining why a leak at the exhaust is Not A Good Idea At All.
You're p*ssing hot exhaust gases over components that aren't supposed to have them, any idiot can see that's a terrible thing to do. No exhaust will ever sound the exact same as a sodding leak, neither will you ever be able to replicate that tone, so why bother? It has no purpose whatsoever.
There are a billionty different exhaust for the Zed out there, and I guarantee you one of them will meet your tone/noise/looks demands. You're not trying anything big or clever by this, it's the kind of thing I'd expect a 17 year old to do on his first Corsa.
Get out there, listen to a few different exhausts on a meet, and pick one. There's plenty out there for £600 already that are quality.
As far as i can see you have a choice of either crapspeed,cobra, or scorpion for sub £600. Unless theres more im not aware of ( please feel free to enlighten us) that hardly constitutes plenty.