I've looked into that set up and the only real disadvantage I can see is that their systems are not currently smog legal in most states. If you're vehicle is registered in a non-smog area then it shouldn't be a problem.
The biggest advantage you would have with this set up is the cost of repairs and availability of parts (i.e. sensors and such). Their system uses the O.E. GM stuff which is less expensive and probably more readily available anywhere than the Toyoat stuff will ever be (like a MAF or TPS both very expensive in Toyota stuff but not the GM stuff).
Another advantage would be less work for the conversion (no manifold swapping, fuel lines, tank and so on...
) and not much to get rid of when you're done. In fact, you could keep the stuff that comes off to convert it back if you had too. Say...to use the system for your next truck.
JMO
If you get this et up I'd like to hear back from you as to how it works.
