Hi all I think i am having a problem with my exhuast , when i start the car it runs fine ,But after about 2-3 miles their is a noise from the centre area around the exhuast pipe area ,I have checked to see if any thing has worked loose ( all is very tight) , it sound like a hammer drill (or the big ends have gone ). starts about 1500 revs & goes faster with more revs , I think the noise is coming from inside the exhuast pipes from one of the small boxes in the centre area . Has anyone had the same problem

Cheers

Andy