Quote from Murray Ruggiero:
I have done a lot of work on this topic over the years and in fact wrote one of the first articles on trading the equity curve back in the mid 1990's. Equity curve filtering of a trading system create a feedback loop. One problem is that since your filtering the system you need to set up an unfiltered mirror version. This often requires complex code and writing a custom backtester within the system in most platforms. In TradersStudio I added a second backtesting channel for this. I created two sets of buy,sell,exitlong,exitshort instructions. One, which shows up on the backtesting report and another, which are virtual, you, can access all the statistics but they do not affect the reports. This makes it much easier to do equity curve filtering of a system in TradersStudio.