BD Power - Product: Top Speed Eliminator
Owing a 2003/2004 really limits the options for recalibrating the speedometer. Today installed this unit from BD Diesel and I was able to get it my speedometer within 1.2~1.5% of what my GPS was indicating. Given how small the adjustment knob is, and that my wife's 40K mile 2007 Mustang GT is 2% off, it was close enough for me.
While I don't really care for the type of connectors that were supplied, it is an all inclusive kit. The only reason that I used the screw together connectors is that eventually I am going to 4.10s, and this part will come out. About all I really had to buy was a fuse tap (the supplied one wasn't going to work) and some double sided tape. No real big deal.
Not only is the speedo corrected, the odometer reads accordingly. I did what Google maps called a 69.9 mile trip and I logged 68.9 miles on the trip odometer. This works out to a 1.5% error rate. Considering it was 9% off prior, that's pretty darn good.
The only down side is that the Top Speed Eliminator is not an optional function where the speedometer correction is optional. Because I use an SCT, top speed eliminator is irrelevant.
In conclusion, it's a good part and $95 isn't too bad of a price. Putting the inner fender back in SUCKS, but other than that, it was pretty easy.