I’ve been playing with an LS20031 for this purpose as well. I find that it works quite well when driving around on the street, but has significant issues when I put it in my race car… I don’t know if it’s all the exposed metal (and roll cage) inside the car, electrical noise, or the particular track I was at (and my proximity to the wall), but the GPS was screwing up pretty bad in high speed banked turns. It seemed to do just fine at slow speeds, and all the slower parts of the track, but was frequently all over the place once I took the high banked turns at full speed (around 100 mph).
In most of those cases, the HDOP went pretty high, but not always. I tried to reproduce the problem in my street car by driving in areas with lots of overhead obstructions, around tall buildings, through downtown Denver, up a local mountain, etc., but all the data looked pretty solid. I got an error of a few meters at worst. I’m suspecting some sort of multipath error during racing conditions and speeds, so I think I’m just going to try a GPS module that I can connect to an external antenna, such as the GPS-00464 (which looks quite a lot like what Traqmate uses).
To illustrate this, here’s what a slow pace lap with the LS20031 looked like…
http://i42.tinypic.com/e7xo3c.jpg
That’s pretty good. Here’s what a high-priced Traqmate (with roof-mount antenna) produced around the same time… (the differences shown in the maps here are probably mostly just different driving lines, as we had cars going side-by-side through the turns)
http://i42.tinypic.com/c80o6.jpg
But here’s what happened to the LS20031 on some full speed laps… (seemed to happen every time, and some were way worse than this)
http://i41.tinypic.com/2mm9t28.jpg http://i40.tinypic.com/2ii8kyh.jpg
I was hoping to keep things simple and avoid needing an external antenna, but it looks like it may be just not worth the trouble to try to use an integrated antenna. Should work pretty good on a kart though.