The srt6 is faster than the stock srt4 neon. It is not nearly as easy or cheap to mad as the srt4.
The limited is slower than the neon and it will be almost impossible to make it as fast as the neon without breaking the bank.
However the crossfire has more charter than the neon and it a much better "driving" car.
It is a sport touring car not a 1/4 mile racer.
I love my crossfire and I am not trying to persuade you from getting one but don't expect the parts bin like the neon has...
Search some posts here and make sure it fits what you are looking for.
Best of luck.