I think you may be describing two different parts.
One part, called slides, sliders, hifax, runners, whatever you call them, mount on the underside of your suspension rails. These allow the track to glide easily over them and wear slowly over time.
Your tunnel protectors, or heat exchanger protectors, are on the underside of your tunnel, and yes, they protect the tunnel and heat exchangers when using studs, so if your track/studs for some reason hits the top of the tunnel they are stopped before they rip a hole in it
So slides are originally on your sled but may need to be replaced when they get worn out right? Tunnel wear strips do not come from the factory but can be added? How hard is it to add tunnel wear strips? Also where are the heat exchangers-both in the back and the front right? I know my sled on the front one the protective plate has been ripped into by my studs which are too long and the track was too loose. Does it make sense to put the wear bars in the front by the heat exchanger andin the back?
Yup. Slides are plastic, and get worn out. Don't let them get too worn out or your track and suspension rails will go bad.
Yes, you can add tunnel protector strips if you don't already have them. I don't think you can put them on the front. Do you have a polaris indy? my sled has a heat exchanger there too, and it is beat up pretty bad. However, I'm not sure what products you can use to protect that. you're better off getting smaller drivers on the axles, so there is more clearance in there for larger lugs and studs. Otherwise a protector will just add more clearance issues in that limited amount of space