Welcome to Nico!
The Z is an IRS car so it's not going to be as good of a launch as what you'd get from a solid axle car like your dodge's. Also being a roadster means you have more chassis flex than a hardtop car. No matter what car or chassis you use there are things to do to improve traction out fo the hole. TIres are the biggest thing, a 400 treadwear all season with 32 psi will never be anywhere close to a wrinkle wall at 12 psi. Of course there are drag radials that can provide a happy medium. launching on a street will never compare to launching on a prepped track surface. Weight, less weight means you get out of the hole quicker but where that weight is plays a role too, you want as much weight above or just in front of your right rear tire as this is where the lift of a launch occurs. Suspension, drag racin generally you want pretty stiff rear suspension in the rear, in stock form neither ar is ideal but either can be improved with aftermarket parts, the didge would also benefit form traction bars to limit axle twist. The differential, you didn't specify a trim level all but the base model got a VLSD, which isn't much better than an open, the aftermarket has torsens, clutch types which are much better. I'm not sure what came in the dodges I'd assume it's either a clutch type or some sort of locker which would be better, and the aftermarket for the dodges are more drag centric so i'm sure a spool is available which would be the best and cheapest differential for drag racing, or course it's terrible for street or track driving. The Z will outrun any rear drive dodge on any autocross or road course but the traditional solid axle cars would have an advantage on a drag strip.