Skoda Fabia SDI Exhaust blowing noise

[daves sdi]

I have a Sokda Fabia SDI 2003 with 70000 miles and it has started making a blowing noise from the exhaust, however the exhaust is not leaking its also noisy from the tail pipe, its a complete new exhaust including the cat, its had a new cam belt and i have checked the timing twice and cam and pump are both spot on, I have removed and cleaned the EGR valve and it works fine I have also applied a vac to the EGR and the engine sounds the same with the valve open or closed. the engine starts and runs fine pulls fine and is doing around 60 mpg , has anyone any ideas?

Thanks Dave