so i installed a chikara header (i was ona budget) about a year ago. For the last 5 months everytime i brake with the clutch engaged and the motor winds dow to about 1300rpm i get the most annoying rattling sound imaginable. when the car is off and the exhuast piping is cooled down i can grab it and try to shake it but its tight no slack at all. the heat sheild from my catalytic converter has been removed. any suggestions?

 

bump....

 

possibly your cat went kaput?

 

Look at your donut gasket. Mine went to the pot and the exhaust started rattling.