Broadly speaking you can divide contollers into two main categories piggyback and standalone.
I think the only complete true standalone out there and correct me if I'm wrong is Impulse, the rest are some form of piggyback system. For those of you who don't know the difference or who may be new to the whole turbo thing, a piggyback retains the original ECU and the auxiliiary fuel controller runs on top of that where a standalone replaces the entire stock unit with a new brain.
One Stop Performance has had a complete standalone ECU system on the market for many years how and it is proofing , just not in the mountains.
I run one of his engine , turbo and standalone ECU,s , i try not to come on snowest much about any fueling system , as this type of topic usually starts a !hit show.
I do agree until someone ( turbo kit builder ) gets one of these complete standalone ECU,s working flawless for mountain riding , it should not be sold to the consumer (this should go for any product , but in the turbo sled market the consumer in many cases have been the testing grounds and paying the price of advancement)
I have 5 years working with a complete standalone ECU on a 4 stroke turbo sled in the mountains , all i can say is , there is a lot involved in getting a standalone ECU tune to work in a turbo sled in the mountains and for
now unless you know how and can spend the time doing your own tuning , do not go this route.
Now for the performance part of having a complete standalone ECU , all i can say is i think my sled set up works pretty good, my engine runs stock piston , no head shim (11.6:1 compression) stock head , a GT 3076 turbo ,dual stage 700cc injector , my tune is made for running C12 up to 25lbs of boost, i think it works pretty good .
I have not been around some of the other system out there now , all i know is something had to be done with the fueling system that came on my turbo kit that i got 5 years ago and this is the way i went , i try not to be so close minded as some