Just got my Lt-8 in the mail today. The previous car it was on was an S5 fc which is the same model as my car. Sadly the ecu only came with a wiring harness and no commander. Would it be okay to drop this in the car and run it for a week before I head down to tune it?

 

You run the same set up of the other car?

 

As long as your porting is similar and you use the same injectors at the same fuel pressure, it should start and run the car light load fairly well. Even if a few things are different it should still run the car well enough to be driven. But obviously, it probably won't be a very pleasant experience until it is tuned and you need to stay out of boost.