Actually, this ea absolutely thrives in strong trends. It's the ranging periods that will cause a blowout.
Another note, some credit ought to be given to the fellows over at forexpeacearmy that originally came up with the idea and also the coding. This ea is practically a duplicate of the ea over there except without the names in the code.
Nick,
Please have a look at this thread where the idea and also the ea originated...
Williama's Trading System - Forex Peace Army Forum