okay yea i figured that, i switched my UE version to 5.2 and got everything working so far.
chaos updated some stuff in its physics thing, so i will have to update some references soon. but overall its great stuff. although i figured that version i believe 1.6.1 is having a bug with the high rpm rev thing. although your sound system so far is great i do believe its not the best way atleast for me to do engine related sound stuff and id like a checkbox with the next update that will come to untick engine sounds.