Rear suspension design is the biggest weak point. Where the strut attaches to the trailing arm is super low, so it will get sprayed with enough gravel to eat away at it and is prone to hitting larger rocks. I ended up attaching some aluminum plates to the trailing arm with a custom bracket to act as a shield. The bolt holding the strut to the trailing arm is also prone to backing out under the vibration. You will need to check it every opportunity. I didn't and that ended my rally day.
At this time, it was probably about $8k - $10k on top of the cost of the car. Way different today with how much costs have come up. Cage costs alone have pretty much doubled.
