A long time ago there was a set of before and aft piston pictures, from running ARX in a high mileage Honda Civic Motor.
I believe they were posted here as well as over at ARX. However, over the years, I think that was in year 2000, the pictures have disappeared.
Its too bad because they were very good pictures. I say that because I was present when the crank was dropped and the pistons were dropped out the bottom. In this test, the ARX was run only 200 miles and the difference was already night and day.
It is very much a pain in the rear to drop out pistons, may be more so to reinstall properly. This is why we continue to see only under valve cover photos.
I don't know how many compression tests have been done and posted over the years, may be 25 or 30. There used to be a nice set of top end picks, with compression tests, as a sticky post here in this section. Aaron was the name of the guy that did the test. His car was a high mileage Nissan 240Z. He was nice enough to photo the top end at start, after the cleaning phase, rinse phase, etc. times two applications.
Personally I rely more on the testing numbers, than on pictures anyways. There seems to have been alot more motor pics of ARX over the years than any other product talked about here. I think that ARX has a fairly solid reputation to stand behind at this point.