When to shift?

Chassis dyno. What's that cost?

As I said in my post, "there are other ways." Even I have a couple of G-techs that I've bought used, locally. I have less than 150 invested in the two of them. One is an older model, the newer one is new enough that it has data recording. 'S all you need to run a baseline, along, of course, with either a bit of track time, or a "stretch of road."