I have been paper trading a similar system. At close of the day, place a sell below the previous days low, 3 PIPs lower. At the high, add 3 PIPs plus the spread to the buy. 20 PIPs TP and SL. Trading the EUR/USD, GBP/USD, USD,JPY, USD/CHF and AUD/USD. Watch the spread!
Bottom line, about 63%...