When I accelerate in my 2000 bugeye I get this dull rattle only happens when you accelerate in wrong gear and engine is labouring, example driving along in 4th gear at 35mph then accelerate sounds like its pinking like older cars used to do when you put cheap petrol in them, other than that car goes great with no other problems , help

 

Sounds like the exhaust heat shield rattling. Have a look on the forums for details.