Re: shift lag!
If you are hitting readline, the computer is flaking out and pulling fuel/timing/panicing before it blows up....and when you hit 5th it hasn't recovered yet so it bucks and lags.
The important thing to fix this problem is don't run to redline.
"When I know more, I'll be forthcoming. Or I won't be forthcoming, and I'll be honestly deceptive." - Les Miles