I know it is too late now, but I am running DIS-4s on my supra and truck. Getting them to work properly was difficult, I had many issues, but after a month I got them sorted out. The culprit was the stock coils could not handle the voltage output of the MSD. They were arcing off everything under the hood! I had a good ground and I tried 3 different coil packs, one very low mileage which held 26psi just fine. Difficult to see the arcing unless you like standing outside your car in pitch black with your hood open and car running. So my parts list was the DIS-4 $400, two tach adapters $100, and 3 MSD GM style coils $120, GM terminal ends to install on my NGK wires $10. Its actually really simple to install once you know what's up and the MSD coils are better than the stock one's and cheaper than new Toyota coils.
I would have went the DLI route for price, but I needed the 2-step and timing functions of the MSD for what I do. My whole reasoning in getting the MSD was for those features, spark benefits were icing on the cake in my case. Both units work great so far, haven't been to the track with them yet though. Soon as the weather warms up!
Install pics:
http://www2.davidconsentino.com:8000/Supra/DIS-4 Install/