Thanks for your tips chap, I asked the mechanic to look into all that. Its turns out the honeycomb in the front box (of the centre section) has broken up inside. The previous owner of the car had replaced the centre section and the backbox in August 2011 so its lasted 3 years. Ive found the centre section for £45 via ebay, same sellers i had bought my flexi pipe from. Its £10 more at euro car parts and I may just go to them as its local and easier in case i need to make a warranty claim.
Question is do i get a hoffman race tube for some noise or stick with the standard centre section? Im worried il get the racetube and itll be too noisy/chavvy! Help chaps, im confused