Originally Posted by undrgnd

Running with a CEL is no more ghetto than replacing a perfectly good cat with a less reliable, more expensive, HF one just for, what purpose exactly? 5 hp at 7100 rpm? Good thinking. In a lot of cases the CEL condition is not hurting the engine at all, and clearing it with an OBD reader is by far cheaper and more reliable. ...and I like my coat hanger antenna, less drag, about 5 hp at 155 mph.

Originally Posted by davidv

When you remove the OEM catalytic converters (lying on the floor) and look at the ends, you will wonder how any exhaust gets through the damn things.

Are aftermarket catalytic converters worth, say, 5 additional peak horsepower? You decide.

Can I feel a 2 percent increase in horsepower? Of course not.

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Originally Posted by Z1 Performance

less reliable? more expensive?

I've had my Ultimate Racing high flow cats on now for 2.5 years...over 40k miles, not a single problem. Sweet sound, lighter than stock, no rasp, perfect fitment, no CEL ever, car passes emissions, no foul odors, no stained bumper. They also have a warranty on them.

Do test pipes make more power? Yes....a couple more, nothing overly significant. But, a good set of high flow cats are money well spent for lots of people who want the 90% of the gains but none of the potential downsides