I'm looking at giving my exhaust system a little over-haul, new cat, new muffler, and hopefully new piping. Found the parts I want, but the cat's inlet/outlet diameter concerns me.
All the aftermarket cats for a 1991 318is are showing a 2" inlet and outlet even though our systems are 2.25". My question is what size is the stock cat's inlet/outlet?
Why would it be smaller than the rest of the piping?
And, would this hurt performance?
it just has me baffled, and I don't want to buy a cat that will hurt performance compared to the stock one.
All the aftermarket cats for a 1991 318is are showing a 2" inlet and outlet even though our systems are 2.25". My question is what size is the stock cat's inlet/outlet?
Why would it be smaller than the rest of the piping?
And, would this hurt performance?
it just has me baffled, and I don't want to buy a cat that will hurt performance compared to the stock one.
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