The engine in the SARS ute is similar to the Merc m111.970.
At 110 kW the engine is suitable for low grade petrol.
This chip claims 122 kW from the 2.3 on high grade fuel.
http://www.powerchipgroup.com/datasheets/5/MER0077.pdf
So there is at least a likely 122kW in the Actyon 2.3 litre.
I would guess a ute with 12 extra kilowatts might be able to pass a ute with 12 less kilowatts down the length of the straight on most NZ tracks.
Are the utes wheel dyno tested before each event or otherwise checked for conformity?
The difficulty of passing is readily apparent in the Aus supercars where they are tapped out at 600 hp and going the same speed, almost every passing attempt is a crash or brake lock up when it does not work.
A push to pass (run 550 hp and 600 hp on the pass) on the Aus SCs might make the racing look better than the processions they have had for years.