8) using the megasquirt you can install a flex fuel sensor and be able to run E85 if you like, or E10, or something in between, without changing the fuel maps. like the factory system you can have an ignition controller as well. the megasquirt is also simpler than the factory system, but doesnt use many of the factory sensors and thus is not emission legal technically.
if you want more efficiency though, start by porting the stock heads and intake, add a set of headers, advance the timing to 10-14 initial, and install a set of 19lb/hr injectors. that should net you more power and fuel economy without having to change over to a new system.
if you have never used the megasquirt before, it is a system that you program. there is no factory settings for it.