Alright. So I was running up 95 N last night when a 350Z felt the need to run up on me. Now me not being able pass this taunt up i droped into 4th and got on the throttle, easily pulling away from the Z. Now my problem starts here when i shifted into 5th my boost spiked and my tach shot straight up to 7.5/8 grand. I backed off the throttle and everything returned to normal, my car still ran strong for the rest of the drive home. I am totally stumped on what happened HELP!

 

Need a little more detail here when you say spike you mean it went upto say 15psi?? ( and you normally run 10psi),, and also when you say your tach shot upto 8 grand do you mean it did it instantly like your clutch is slipping?? (it sounds like your clutch is dieing or cant cope with the power your running mine is doing same especially in the upper gears like 4th and 5th)

 

thanks for the post it hadn't even crossed my mind that it might be the clutch thats probably exactly whats happening.