The most common thing that has rattled on mine was the heat shield between the muffler and the trunk......

 

Na the noise comes from within the pipe and can be heard more towards the front of the exhaust then the back

 

Guess it's time to pull the pipes and give them a shake

 

Unfortunately all parts have been removed and replaced be it temporary and the pipes coming out fully inspected

 

Well a little update rattle is still there I took it back into the garage for a service and they checked it and they claim its the note of the engine combined with the system and most likely magnified by my rb header which is strange cos I've swapped every part of the exhaust system out and it's still there it's starting to look like decent sound is not meant to be and il have to resonate the crap out of it maybe even swap out my borla for something less like a rev8

 

Right im back and still battling this and the rattle is getting worse its but im narrowing it down a little it only kicks in around 6k and only when im moving so revving doesn't cause it also im starting to experience power loss around 7k and she is back firing every so often now and not a quiet pop a full gun shot bang.

 

Ok thread revival the car has been out of action for over a year due to a dead engine and no funds but she is back and the rattle and buzz is still there now ive found the iddle rattle it was the ssv which I will be replacing but im left with a high pitch metalic buzz that hits about 5500 rpm sooooo......
Any ideas and to update I have an AEM intake fresh built engine , racing beat header originally a cheap header , both a racing beat unresonated mid pipe and bhr midpipe (no cat) and a borla cat back.

I cant see it being the borla as the sound is changed when switching the midpipes over I am going to try some washers on the header bolts to see if I can nip them a little tighter and see if that helps.