I want to know if the roll cages in forza are worth putting in for drag racing because even on the lightest of cars they can put on about 150kg or 340lb
This may be the better place to ask this question 
(If you don’t get an answer)
I go off of benchmark for drag. Some cars need the rigidity, some cars don’t. IMO.
I use the cage to improve launch times…Helps it hook better on some cars
From my testing it depends on the car.
Some cars (usually older cars) accelerate better with roll cages. Don’t just go on benchmarks though. Most of the time they are indicative of on track performance but sometimes they lie so test on the track.
What Kru said,cages help with launch times!
Cars with 51% + distribution, yes on pretty much every single one. Cars with 50/50% distribution, no with pretty much every single one. Cars with 49% - weight distribution, no, with every single one. You want as much weight on the rear as possible, so if the weight distribution goes down towards 50% it’s worth it, but if it goes up towards 50% you don’t want it.