Im putting frame connectors on the challenger. I was wondering if I need TQ boxs as well? Im aming for a 500-550hp 440. Do i really need them or can i get by with just the connectors?
Chassis rigidity is not necessarily something you can discretely call good or bad. You could do nothing and it'd probably "get by" just fine, but it's all in what you are after.
If you want to cut down on creaks, pops, have your body gaps remain more constant and have your unibody stop acting like a suspension component, then adding stiffening components is always a benefit. That being said, if you're working under the car and have things torn up, then torque boxes are generally considered a good idea.