Well, I'm gonna give you some hearsay anyway, since I don't know of any VR-4's with a Haltech. My friend Ricki had a '94 RX-7 that ran 11.40's, and he had a Haltech on it. I talked to him once about using one on my VR-4 since I found one for a good price. I was told that you will end up replacing most, if not all of the sensors on your car, as well as need to have it dyno tuned for each level of boost you want to run. Al in all, I was told the cost for purchasing/installing the unit would be around $3500. Money may not be a problem for you, and if not GO FOR IT! Everything I've heard about this device for tuning has been positive, and was told it's the way to go, if you can do it.