Charles,
I personally use Pi Research, this from investment 10+ years ago. Good equipment works for a long time, multiples of cars and karts.
A few years ago I worked with a fellow who ran CDS, Competition Data Systems eq. If and when, I will look this direction.
I have also been looking in the direction of Racepak, I believe the same folks as MSD in Tx. Or owned by the main company.
Not to advertise but these folks are very good
www.veracitydata.com One note: the software to anaylise the data is a tool, take a look at it also.
A very good book on data was published by the SAE, I forget the author. Can be usefull to show you what systems can do.
I will look up the author later today when I go to shop.
John