The quiet core insert can be used with most (see below) DR.D exhausts. The insert can be installed and removed very quickly. And as the name suggests it helps to reduce the sound level. Although you will experience a mellowing of the power by installing the insert there is not a significant power loss.
* This product does NOT work with a 2010 CRF250 , WR250X 08-09, DR.D Mini Bike or NS-4 systems.
** Images are for reference only, they are not model specific. Actual quiet core insert vary slightly from image provided depending on model.