well i have alot of exhaust noise coming from the front end and had it check out for any possible blowing from any of the joins on the exhaust as i recently had a blueflame system put on but there was no signs of any from that so the bloke who fitted the exhaust said that it sounds like the exhaust manifold gasket has gone, when i rev it it kind of makes a hissing/ticking noise, doesn't sound healthy at all!