Whats the best catylac converter size

[88Tsupra]

Ok this is the story... i bought an Apexi exhaust Tip its three inch piping of course and im going to have a custom pipe installed for it..but i also need a new cat. and i was wondering if the size of the cat would make n e different on sound and mainly performance. I know a shop dat offers about three or four different sizes. theres a reglar($100) size a medium($75) and a small (25) and its really small i say length wise shoter then a foot cat....i have about lets say 200 to spend for custom bend and cat...without going over that price dramatically which one do u guys recomend in standard cat and high performance cat....
thank you