Old 2010-era mods (pre-v2.3.1) and any mod that replaces carphys.tun without a backup—those cause the infamous "garage crash."
Most mods made for earlier versions like 2.2.1 MWM or 2.3.0 LE are compatible, but these packs are specifically optimized for 2.3.1. street legal racing redline 231 mods best
Here's an example of a well-rounded 231 engine build: Old 2010-era mods (pre-v2