Hi and welcome to Cliosport.net, I'm assuming that your car is the 182 version on a 04 reg, and it's quite common that they rot, most people replace them with a stainless unit as it's cheaper and they don't rot again in 2 years !
Now there's a load of opinions of what's good, if you want a very quiet system I'd recommend a RS192 system, good size very nice noise but not over bearing , I have what I'd class as a middle noise system, which is a K-tec/janspeed system can be heard in the car and rather loud when high in the revs, at idle a nice burble!
If you want to go very loud , the only way is a yozza / BTM exhaust , and you will make everyone hear you ! Lol good luck with the choice mate
Dean