Okay, here's the deal: As discovered by myself and Baker, this device requires modification of the male connector in the throttle housing on an R53. Maybe the OP has an R56, which may not require the mod? One needs to be extremely careful when handling the harness, or you risk damaging it (as I did) by just trying to plug it in. It turns out one or more, wires pulled out of the pins inside the female connector, rendering the cable useless. A&J was responsive to requests for help, but their resolution was "send the complete unit back, and we will fix it", rather than sending me a replacement cable. Knowing they would claim that i broke it (likely i did), I figured i had nothing to loose in trying to repair it, and disassembled the connector. I DO NOT recommend attempting this: we work with similar components at my place of employment, and have the correct crimpers, pins, etc. Even getting these apart is tricky to do without breaking the connector. i found 4 of the 6 wires pulled out of the pins. Once repaired, the connector was re-assembled, and the installed in the car, and the D1 is working now as advertised.

To sum up:
1. You have to modify your throttle pedal connector to install the harness on an R53.
2. The harness was not assembled very well: there is no way the wires should have come out that easily. This raises a reliability concern.
3. A&J was willing to help, but shipping parts back and forth is not the quickest way to get the issue resolved.

 

Not sure if anyone will have experience with this but I think it's worth a shot. I've had my D1 for a few months and I run it at SP9. I was disappointed with it as it didn't make much difference in throttle lag, even at SP9. Recently did a clutch job and disconnected the battery and ECM as part of that. The issue I'm about to describe did not occur immediately after completing the job, so that's partly why I'm confused. Just tonight I noticed the car felt like it was accelerating more than it should with a given pedal position. As in, when I pressed the pedal maybe 10% to take off from a stop, the engine revs as if I've depressed the pedal 30%. I end up accelerating more than I want in any gear at any throttle position and that's obviously very bad. I also noticed some occasional stumbling in a few gears at varying RPMs and throttle positions, as if I had completely released the pedal and then reapplied it a few times very quickly. With these symptoms, I thought of the throttle controller first and how WMW said they did not endorse it because it wasn't TUV certified. This sounds like a reasonable set of symptoms for a malfunctioning throttle controller. I thought maybe my calibration had been erased when I disconnected the battery, but I checked the unit tonight and it still showed SP9. Recalibrated it anyway and set it to SP4. Still shows similar symptoms, though they appear to be less severe? May just be my imagination, but the excessive acceleration and stumbling are not. Also tried to change it back to normal after driving at SP4, but I couldn't get the display to come on when I turned the ignition on this time. Tried cycling the key several times and couldn't get it to come on. I'm going to disconnect it and test again tomorrow, just curious if anyone else had experienced this with the D1 or if this is some other issue. Can't find much documentation for the D1 online.

 

I've had mine installed for five years, and have had no issues. Is yours plugged into the OBD port? Did you try unplugging the unit there; that should tell you if the D1 is causing the problems.

 

I had one in my car many years ago, and I don't think it made much of a difference. I did not have the symptoms you are experiencing. I did have some weird battery problems that went away when I removed it.

The best way (in my opinion) to reduce throttle lag is to install lower motor mount inserts.

 

It's spliced in with Posi-Taps. I drove this morning without unplugging the D1 and it did not show any symptoms from yesterday. Unplugged it anyway, I'll run it for awhile and see if any symptoms come back.

I have a Powerflex rebuilt lower motor mount and I think it is causing some rattling at idle. I'm going to go back to stock on Saturday.

 

I've had the D1 disconnected for a little while now and the car is still exhibiting the issues. Oh well.

 

Could it be your BPV?