There may be a mistake somewhere in what follows below but I am reasonably sure about it.

The common wisdom is that front travel gain is impossible without aftermarket UCAs. Especially if you ask those who make and/or sell aftermarket UCAs. This may be true in most cases.
BUT, when Toyota released the first TRD Bilstein, they advertised--you can find these via google search--a gain of 0.75" in the front (as well as 1.5" in the rear, which I also got via my Icons there). They said nothing of UCAs.

SO...what is the standard IFS travel on non-Pro 5th gen and FJ? From what I have found, it is 7.8" total travel. You would expect it to be evenly split or slightly privileging down travel. Unfortunately, I never measured mine stock.
BUT: I did measure with stock shocks and Dobinsons springs. The lift I got was a bit over 1.25" and the travel was a bit less than 2.75". This suggests that stock down travel is indeed around 4".

When I installed 6112s with 600 springs, I had 1" of actual lift and downtravel of 4.5". This suggests that the stock TRD version is somewhere around 4.5-4.75" of down travel.

It will be less with 650lb springs.

Unfortunately, I was not as pedantic as I could have been and it is possible that I am making a mistake somewhere. However, statements like "you must have UCAs for extra travel" have zero merit when discussing the PRo and the 6112s.

Btw, forget racing and extreme rock crawling, front wheel travel of 2.75" was really dangerous even on moderate trails. So long as you are always straight up/down and going over rocks it is fine but the moment you must go around something on a tilted slope, it makes for a harrowing experience. Similarly, it makes you lift wheels on any undulating enough terrain. I drove difficult terrain with that setup but it is really more suited to the mall I came from Subarus so I initially underestimated the importance of travel in non-racing use on these rigs. Lifting wheels on the Subaru was something that happened all the time and never caused me any sweating. Not so with the high-center of gravity 4R.