not sure if the GTO's 6spd is any different to that of our Monaro.. but at 100kmh/60mph in 6th your doing around 1500rpm.. not sure what the aerodynamics are like, but regardless -- with that sort of gearing and power, it should have much trouble cruising past 155mph.
in the uk, the Vauxal Monaro (another re-badge) in highpower spec is actually limited to 178mph.. so there you go 8)
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