i need to know what the stock y pipe size is on my 97 firebird formula, and what the size is of where it gets smaller at the end of the pipe.

i need to find a 3" pipe that goes over the y pipe, and goes into the i pipe.

 

the y-pipe is 2.25 and the intermediate is 2-7/8

 

i just read somwhere it's 2.75? i have a 3" cat back system now and i need a reducer because there is a gap in between the i pipe and the y pipe. the y pipes end fits inside the 3" pretty nice.