[dazee]

I did some quick comparisons for how they perform without magnets.  But first some disclaimers    I am not a racer or tuner, just enjoying the hobby, so probably an awful lot that can be done to improve on these times.  The cars were raced as is, just minus the magnets from their normal state where I use them.  For the Slot-It and Carrera, these are normally raced with one magnet left in.

The Slot-It had stock tires on and clocked a best time of 23.571
The Carrera (Z4 GT3) had a set of Supertires on and had a best lap time of 24.486
The Plafit Beetle had the guide trimmed down to let the front tires hit the track, and a set of home made tires.  Best lap of 21.826



Clearly the bigger guide and the extra weight low down helps it perform well on my track.  The other cars would definitely benefit from adding weight and tuning, and a better racer!