95 you could go into the pcm and set the timing 0, -5, -10 from base to help eliminate pinging. It was definitely a power robber and the customer often returned and would live with a little pinging. Can’t remember what year they took that away from us with the irreversible flash.... was hell for corporate to keep that archaic design emission compliant. I looked into about every option avail to get more tow grunt for my 95 5.9.... but alas, nothing much for return in investment and it turned into a diesel payment.