The RC servos definitely have travel stops - they're built in for airplane use, since every linkage is different. Get the big ones for the 1/4 scale models - they're stronger. The servo will respond to more motion input after hitting the stop with no motion. It knows it's maxed out, so just won't do anything.
Travel stops for the injection stuff? definitely. Usually they're part of the throttle body assembly, though, so this might not apply for you.
Now the good news - if you decided to go the automotive route, there are travel limit microswitches usually for idle and full throttle operation - to tell the computer that it's in idle mode or that it should go to power enrichment. These are generally mounted on the other side of the throttle body shaft from the cable pulley.