On the whole yes 8) but it depends who makes them.
Tamiya and HPI make RTR (ready to run) models that are good but you obviously pay a premium when the manufacturer builds them for you and you don't have a choice of what stuff goes in it.
In the end it's like everything - the more money you spend the better/faster the car is.
Check out Ross' home page on www.tamiyaclub.com (Maxxed Ross)
It will give you some idea of what can be done :approve: