I have been told in the past that a cut out on long tube hedders with no cats will not harm the valves. I am also told that this will harm the valves. What is the difference in the newer camaros and the older 68,69 camaros that this wont happen? The cold air still hits the hat valve right??? I don't know, thats why i am asking. I hear that these pops when we are letting off the accelerator are what the problem is. Someone set me straight. Thanks

 

There is some reversion on an open pipe but there is no way fresh O2 would make it all the way up a header primary and into the exhaust port. You will not "burn the valves"

The most notable "pops" you here on deceleration is probably from the decel fuel cutoff that the PCM uses. Basically under zero throttle/low load the PCM cuts fuel until a certain speed/load is reached or you apply throttle and then it reenables the fuel and you hear the "pops". These pops are influenced by fueling and ignition changes under heavy vacuum to load changes and is nothing to worry about.