Since it is piggybacking the ECU and achieving result by modifying engine sensor output before it gets to the ECU (just like the AFC), it does not have seperate timing and fuel control. It also suffers once you change the boost level so you can't optimally tune it for more than just one boost level. The trickery it uses to manipulate the ECU also makes the tuning process much more time consuming; something you dont want on a $100+/hr dyno..