orrrrite i have an issue thats been bugging me for a while now

i have this friggen rattle SOMEWHERE which only pops up at idle (around 800-900 rpm) after driving a bit...BUT if i up the revs to a grand it dissapears, it also dissapears after about a minute of idle. now im assuming the worst so i try to drive as much a granny as i possibly can, if not i try to just not drive at all

could it be something as simple as the cat rattling a bit after a bit of spirited driving (had a bit of heat and exaust pops go through it) or does it sound like something internal?

ive been thinkin of calling Sik 'em Wrex racing in mandurah to book her in for my front susp' would it be worth asking them to find the said problem?

Cheers ppl, Nathan