[Kevan]

Graham, it would be much better to put this in it's own thread under the Proxy Racing as this thread is currently about post charges.

Some wood tracks also use magnetic effect, those tracks that use 'magnabraid' is copper braid with steel braid woven in.

We have a mag effect limit which is easy to reduce with steel shim on the bottom of the motor but you can lose ground clearance.  You can also lose some mag effect but not as much with shim on top of the motor also.

We do allow high mag motors on the clubs wood track (magnabraid) but for every 25g of mag effect you lose 1 lap per heat so everyone choses to shim the motor or not use high mag effect motors at all.

Our Rally stages have copper pickup tape so it's not a problem.