I wouldn't do it either. I can tell you that the rough idle is becuase they probably didn't ease the injectors so the ECU would compensate for the added fuel going in and also didn't add the more airflow coming in to better the performance of the bigger injectors. I just went thru this last week when I added bigger injectors, but I also added a bigger AFM and intake. I would definetly pass on it. There are far better cars that I've seen on other forums that are worth a little more but are very well kept and for a pretty good price.
Unless you want to be busting your butt on this one