It doesnt include slippage, however, it is very reasonable to expect to be filled with $100K if you're trading a liquid stock (eg: C, FAS, GE ,FAZ, BAC, etc) . I traded with $100K per trade for months last year and was always filled within a few seconds. Total trades were around 500.
The slope of the equity curve is meaningless. The slope is just a relationship between your time and equity scales. It IS important to have an equity curve that is a straight line if the amount risked per trade is equal. If the amount of risk is a percentage of capital then the equity curve on a good system would be a near straight line on a log chart.
tell us about: how many trades per day? if it is just one trade, then is the system using the open/close price? if it does then that's the problem, as in most cases those prices are not tradable realistically . it averages down positions? let us know BTW you have to add slippage (2 ticks minimum) and comms.
the moment u trade it, it will be sloping downhill. really trust me on this, you can give it a try with min $$$$
You need more data. 6 months is not enough(make sure at least mid 2003 is in it). Slippage in stocks for mean reversal 0.5 basis points on your turnover and in trendfollowing something like 1 or maybe even more. Try duplicating your results in excel.
I had a system once that looked like this, also with some simple rules. The rules were: 1) wait for HOD and go short 2) wait for LOD and go long For some reason it didn't work when I tried it live ..seriously, the only way to know is to test it live on small size. I suspect there's some hidden pitfall here, but maybe you've found a great system.
You can use this simulator to see the tradeoff between RR and % wins... http://www.hquotes.com/tradehard/simulator.html