The best approach is not to worry about the overall output readings on the the dyno sheet but have a tuner who's got the power curve right.
If you want to know how much power you're making, take the vehicle to the strip and make a few passes then you can calculate the output at the wheels.
Or find a shop with a hub dyno which removes factors like wheel spin, strap down, rolling radius & tyre pressures from the process but are still not totally actuate as they reduced vehicle inertia due to the removal of the rims and tyres.
Hub dynos also tend to offer up higher 'at the wheels' output readings compared to the roller dynos which may please some owners.
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