ok firstly mate if your talking about the factory gearknob the top of it does not come off, the whole knob to come off must be twisted anti-clockwise it may be a bit stiff at first but u will get it, and the reason your magna done burnouts running 98 premium is because it is a higher octane, im in Tas our normal unleaded is 92 octane it doesnt look like much of a difference but it is, if you had of put octane booster in aswell as that it woulda baggd em. lol
If it has a T5 then twist anti-clockwise. If it has a getrag then grab hold of it and pull straight up. If the gearbox is factory then it'll have the T5, but im not sure what you're referring to when you say removing the top of the knob as they're solid rubber.
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