Figure instead of paying $400. for a GPS speedometer gauge/kit I would find a cheaper dash mount GPS/chartplotter for a little more. Just wondering if any will save top speed and if I can find one in the $500-$600 range?
Thanks

Garmin 546 will store average & top speeds
Around $900

http://www.race-technology.com/ax22_8_938.html
I think this will do the trick and you will be able to expand the system as your budget permits.

Look at the garmin 640. It is configurable and mobile. You can flush mount on dash. Also keep top mph stored and has full color chart plotter with maps. Got mine online for 650. It has all the functions of the larger units in a small mobile package.
I got tired of my gps speedo going out.

have had 3 garmin's 400 and 500 searies. all saved stop speed. even think my hand held does also.