You have the backtest for a Sharpe 4 strategy?
Actually, the backtests are currently coming out with a Sharpe of 8, so I'm inclined to think there's something wrong with them. It's quite challenging to backtest market making though. I've got a naive simulation (similar to what I did for futures/trend following). I'll try to build a more elaborate simulation using this https://github.com/paritytrading/parity , and try and simulate latency.