I bought second hand, and got a mild steal 3" bell-mouth dump for $60 and a stainless 3" cat-back with a large oval mid, and at the diif it ups to 3-1/2" with a short cannon for $200.
Then I bought a new catco 3" flanged cat for $175 off KMS
= brilliant quiet system for a grand sum or $435...
at least look at S/H options before you spend thousands