Trueno AE86 Turbo with RPM Tachometer Lag

Toyota Trueno AE86 RPM Tachometer Lag My AE86 Trueno "Dorifto-tron" doing some accelerating. Notice that the RPMs stop moving for about a second right after shifting, yet the speed continues to increase steadily. Apparently there's a problem with my tach. Any diagnostic comment theories would be appreciated. Thanks. ** EDIT ** -- I'm beginning to believe that it is my CLUTCH that's burning out. I still have the stock clutch in there, with an Exedy Stage 1 ready to go in! ;D ** EDIT ** I don't know why some people are bashing this video when it isn't a video on how fast I can accelerate, it's a video showing the lag in the tachometer! I wasn't even at full throttle for crying out loud! The care has a GZE supercharger motor from an AW11, but with a turbo. This was when I put in the T25 turbo, before I blew it's seals and put in the Skyline turbo replacement. I don't get what these people are trying to say? That my car isn't turbocharged?? I don't get what their problem is...