Because of this tread http://www.toyota-4runner.org/3rd-gen-t4rs/146022-3-4l-trd-supercharger-thread.html
I wanna supercharge it. Now I've looked at review on this gauge tester and everyone said it sucks and reads way low, it also docent help it's used multiple times and probably taken apart many of times so I'm calling it the testers fault
If it helps at all, you really have to do something crazy to hurt these engines. Hence why you can run a supercharger with no fuel mods and it takes it just fine. I've never heard of any other engine that can do that.
My rig has had a S/C for 8+ years (the PO wasn't sure how long since he bought it with it on already) and now has 192k miles. Runs like a top. Of course though, once I got it I did a ton of maintenance items to make sure it was good shape before I put another 100k on the engine myself.