The advantage of the DUI is that it is controlled by the computer and works in conjunction with the O2 Sensor, Map sensor, etc to advance or retard timing in near real time to changing conditions.
You can order the DUI directly from Performance Distributors, just tell them you want a computer...
Like White Stripe says, try to move it downstream of the collector flange. You're using a heated O2 sensor, so you can move it back and it will still work properly.
You're running heated O2 sensors? Where exactly did you mount it? Some sensors can be finicky depending on if you're running a header or not and what their application originally was. I've read in the past that guys doing swaps and switching to headers had to try different brand O2 sensors to...