I have a system that looks beautiful on paper. Runs off the 2min charts, avg. profit is about .4%. It works on any high volume stock. With no margin, it returns about 70% a year. Backtests well since '98 (as far as SWP can go). I'm not so naive as to think these returns could be achieved in reality. They'd probably be substantially worse. Given my lack of real trading experience, I'm curious-- what factors would make a good paper trading sytem a bad system in reality? How would spreads affect me? With only .4% avg. profit, I'd imagine I'd be taking large hits from spreads alone. How about execution, especially with shorting? Is shorting stocks on a 2min chart problematic? Does the uptick rule become a problem? Thanks for the help.