hey I have a lsvtec turbo and was getting it tuned and on low boost it was fine. put in the race gas and started uping the boost and it would misfire only at high rpm. so I was stuck at 18psi couldn't go any higher because of this so I want to know what could be the issue. it has new plugs and wires on it so anybody can you please help and give me so things I need to check thanks.