I have an XP with the timbersled and the exits. Coil shocks are more consistent(I was tired of air shocks literally changing with the weather). Spring rates depend on what you weigh. The XP chassis combined with the taller ride height of that skid doesn't put much weight on the rear of the sled.
The trouble I encountered was that the 300Lb spring they usually ship was way too stiff for my weight(190 kitted) on a 163. I could stand on the rear of the tunnel and it would compress one inch. Changing to a 250 in my case allowed me to actually use the suspension travel in the rough. The nytro and m8 guys would run stiffer springs because the weight placement is different.
If you want infinite spring rate adjustment and lightest weight, get the foxes, if you want consistent performance and shock pumps make you want to kick a baby, get the exits.
