I've had my RacePak on my Duster for over 5 years and love it. I finally spent the 140.00 and bought the Strange Dana rearend yoke that Jay posted to I can hopefully soon get my sensor and get some much needed info. I couldn't get my ring collar on my stock yoke.

I wonder if it could be done as an Arduino project? Those boards are really inexpensive.
The expensive stuff seems to be the sensors/transducers

What you need to understand about data loggers is sample rate. The greater the sample rate the more info you can gather especially when it comes down to monitoring suspension travel for which you need a high sample rate to get the full benefit. If you want it to tune suspension get one with a higher sample rate.

I'm not using g force at the moment but Im sure it could tell you some stuff about how well you car hooks. Shock travel could tell you more about what your suspension is actually doing.

Tailshaft sensor can tell you converter efficiencey/slip % as well as tire spin.

I got my gear from Innovate Motorsports a while back (innovate) from Greg Kelly and he was great to deal and his pricing was the best . You will have a lot of questions about how all this goes together and unless you play with electronics and have a fair idea of how this stuff works you will need some level of support.

Motorsport Innovations

Greg Kelly also sells generic sensors that are much cheaper than the branded stuff. The Racepak sensors are very pricey.

My car isn't super fast and it generally hooks just fine, but driveshaft data has been interesting to see. I just went from an 8 trigger wheel to a 16 tooth trigger wheel on the driveshaft so it should give good data from the second it moves even the smallest amount. I also recently added a front wheel speed sensor. I don't have a particular need for that data but I had an extra sensor, and I had an available input on my Megasquirt so I wired it up. This will allow me to see % of wheels slip and use traction control in the future if I choose.

I want to add an G meter next. There is lots of cheap options for those, I expect to be able to have it up and running for $50-75 because there is no special proprietary sensors for my application.

I have seen others post this, the problem with good data is you will just want more and more. That appears to be true in my case lol.

I've had decent luck with an Innovate LM-2. I added Pan Vac, Nitrous fuel pressure and bottle pressure. You can get 0-5V analog sensors from Transducers Direct for about $120 with a connector. Two other cars I help with use Computech DataMaxx logger dashes. Real nice stuff that also allows you to use generic 0-5V analog sensors. If/when I add more capability to my setup, I'll probably go that route.