Have you swapped out either the front or rear sprocket on that bad boy? I've had the 929 come up on me at high speeds, but Belle's ZX-6R stays planted above 80 or 90 no matter how far you open the throttle. Also, if you are concerned about head shake or tankslapping, I'd highly recommend a Scott's Damper (if you don't already have one). It doesn't kill off all headshake, but significantly helps in potentially violent tankslapping situations.
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1988 5.0 notch: Previously never modified!!
SN95 block front and rear seats, Mac catback, BBK off-road H-pipe, Steeda castor camber plates, Steeda lowering springs, Tokico shocks/struts, Alpine/MBQuart/PPI audio mods...