I'm not sure how to put your results into context with my results.
First thing is that I wasn't able to go back to the beginning of 2013 like you since I didn't have the data, so mine started Oct 24.
Second thing is that I see your PnL is $36k, but I wonder what this is based on. Buying 100 shares? Even though we are almost a year apart in start date, my study would net 759 ES points, which is $38k, so a somewhat similar number. But when put into context, this was an average of 0.45 ES points per day. This means less than $25 per day, and then I had to subtract slippage from this and commissions, which made it negative.
So I'm not sure how you can account for a generous $10 commissions and come up with a nice positive number.
I understand what Overnight is saying with the idea of forward testing this live. But I think we can easily simulate this a little better. I looked at tick data for the ES, looking to enter just before the close and exit before the open, and I can confirm exactly what price I would get within a 1 tick (since I lose the bid/ask spread). I think what needs to be done before you can trust your data is look at a chart, see where you can get in just before the close and exit just before the open, and compare how this relates to your OHLC data you're using for the SPY.
I specifically don't want to use daily data because I want to see where I'm getting my fill in those last few seconds. I also don't know what data they use to print those daily bars. Is it the 4pm close? Is it the 4:15pm close? Is it the 5pm close? Maybe if you can show the daily log chart for the last few weeks, we can compare this to the tick data of the SPY and see how it behaves if we were actually trading it, and see how the results actually stack up if we were to trade this, not just ran stats on it with historical daily data.
It doesn't make sense that you end up with 36k in profits after you deduct commissions and slippage, and I end up with a negative number.