I have been experiencing popping from my exaust on downshifting lately and occasionaly at a steady rate of rpm just off the throttle and wandering if this might be symptoms of leakage of the pair valve system or guidence as to where else I should start looking for such a problem. No codes are being displayed and other than the noise everything is running 100%
Follow up... I blocked of the pair valves with a plate kit sold on ebay and the popping is completely gone. Problem solved