exhaust pipe ?

Dumb question- from my header using 2 1/4 pipe going to go down to a elbow. My question is do I get a 2 1/4 elbow to match everything? It will need to be expanded on each end if its 2 1/4. Or is it better to buy a 2 1/2 elbow? 90 degree short elbow
you can get 2 1/4 pipe with one end flared, which lets it slide over the same size pipe. Any auto parts store will have it