performance exhaust question

I just had a performance muffler put on my 98 jimmy at Midas, they used the exsiting tail pipe and down sized the outlet of the muffler to fit the tail pipe. I was wondering if I were to get a new tail pipe that was the same size diameter of the outlet on the muffler, would that make it louder and/or decrease performnace because of not enough back pressure?

i would think that a bigger tail pipe would help performance. the y pipe i believe is 2.25 inches and so is the stock exhaust. the cat is 2.5inches. if u get a bigger tail pipe, the transition from 2.25 to 2.5 helps to sort of pull the exhaust out. it may change the tone a bit but i don't know if that would make it that much louder.