Hi Guys

I recently put a new exhaust centre pipe and back box on my car, ever since its sounded like it's blowing, but I've checked the whole exhaust for air leaks but can't find anything. The strange thing the noise stops when I turn right. I've reattached the heat shield as I thought that was causing the noise, but it's not, i've also checked the Cat but that's not the cause either. I've noticed that when the accelerator is pumped/engine revved it sounds like the exhaust is kicking back.

Can someone give me suggestions as to what the problem could be, Would a wrong exhaust part be the cause. I believed the parts I bought where the correct parts and was reassured they were.

I know it's just a noise but it's getting really annoying and the radio won't drown it out, and I'm going to St Ives in 2 weeks time from the northwest of england and don't really want to listen to it for 6 and a half hours.