[Walt Fricke]

As I recall, he found that the stock front strut towers were pretty rigid as they are. The guy who did it was a genuine automotive engineer, but doubtless it would be interesting to use strain gauges or other instrumentation to get a better quantified idea of what forces do what. His conclusion was that the shock towers are pretty stiff as it is.

But like everyone else, I have a brace on one car, and a welded in structure on the other up there.

Movement of the rear shock towers ought not to affect the suspension much, since nothing articulates up there. I'd think there would have to be way more movement than there possibly can be there for coilover rate or shock characteristics to change enough that you could see an effect in your data from the track. Movement in the front can change camber, and cars are quite sensitive to that, but not here in the rear.

But of course things can fatigue and crack. And lots of us are always curious to read the results of testing.