The correct answer is "sort of", "none of the above", and "all of the above". I don't really mean to be a smart a$$, but the answer depends on the source of the water, the flow rate, and the length of pipe. First the source, you will never get more pressure or volume than what it is capable of. This is normally a pressure/GPM curve so you would not expect to get the same volume at 10 psi that you would at 60 psi. Second the flow rate and the length of pipe. There is friction between the pipe and water as the water flows thru the pipe. The smaller the pipe the more friction than a larger pipe (for the same GPM flow rate). Also, the friction accumulates per foot of pipe, so each foot of pipe causes more friction. The friction results in a pressure drop at the end of a pipe. A larger pipe will reduce the pressure loss. However, if you are using this for potable water, you can go to far in increasing the pipe size and end up with stagnant water in the pipes because not enough of the volume is being used. I don't know were this starts becoming a concern but I've heard something on the order of 1.5" to 2" main supply for a house should be the largest used.
Note: There is no friction when the water is not moving so you will get the same pressure at the end of a long run until you turn on the water. - Have you ever turned on a faucet and got a lot of water which gradually slowed down? That is the effect of a pressure loss due to friction.
Bottom line: I didn't answer your question directly. In general if you're just replacing it with no other change, you'd see an increase in pressure. But, the improvement may not be worth the cost of the pipe.