Some people have though....that's why I'm so confused with mine!i already did. I plugged mine at air filter and both heads with rubber plugs inside vacuum hoses and reinstalled hoses. So it looks like its all connected but there is not vacuum through them. I also had to replace exhaust gaskets because i didnt replace them when i installed the exhaust. Also pot setting for fc at 121. I dont think you are ever going to get rid of backfire completely.
And i'd be careful with plugging the hoses...I heard they crack over time. Just a heads up