Hi Thomas. Yes you can. The plug fits into the ARC Air socket and Scalextric have okay-ed the upgrade. However, as Dr_C pointed out somewhere, the powerbase will still signal a power overload if the amp draw goes over the pre-defined limit (2 amps, I think) - so really ‘hot’ motors will have problems.
Most out-of-the-box high-performance cars from the likes of Slot.it, NSR, Thunderslot etc will work with the more powerful power supply, if that is what your aim is - even with their standard magnets. However, if you are trying to solve any power drop-outs on the track, it is always best to start with good track maintenance and use power taps on a long layout.
Hope that helps.