What causes shocks to top out?

So I’ve never done suspension in my life and have been trying to do a lot of research before getting a kit!

so currently I am looking at OME 3in lift but many say these top out hard!so would it be less like likely to top out on a 3in lift vs a 2.5? If I put bumpers will I be fine?

 

I have no idea about anything OME brand but no matter which brand you pick the answer is the same: you need to choose parts that work together, and if you have shocks topping out you didn't do your homework. Those people that talk about hard topping out didn't do their homework.

Here's a good video on Toyota IFS suspension basics to get you started. Good luck, read read read as much as you can it'll save you in the long run. Welcome to Tacoma World.

https://youtu.be/_68Hc8GtLko

 

Topping out hard or often can be several things. Could be valving, could be the shock is extended too much at ride height, over sprung etc. For the best setup, its important to get the correct spring rate for your truck and if its adjustable, not have it lifted too tall.

Below is a link to a few examples with animated graphics to help explain:
https://accutuneoffroad.com/spacer-lift-vs-preload-spacer-vs-coilover-preload/