That........ My daughter's '00 has a CAI, a tune and the Magnaflow cat-back and doesn't do anything like this. There is no reason to remove the catalytic converters from modern cars. They are nothing like the early, very restrictive examples. When Magnaflow was using my (now my daughter's) 2000 to prototype their cat-back system I asked about replacing the factory cats with high-flow cats. They told me that wouldn't help as (even then) the factory units were already of a high-flow design. There would be no flow benefit. This from someone who had something to gain from a sale (even though the exhaust system was free I would have had to pay for the cats).
