StatmanRN

I think it stands to reason that any reduction in flow would reduce power, particularly with the increased volume of FI. To what extent is the question.I'm Sure size, type and condition will effect that.

I do know that when I gutted the cats and went with the x pipe it made a big difference even though I was otherwise stock at the time.

Regarding smell, I found it only really noticable for a month or so. Bu then, 25 years working in the medical field my sense of smell has diminished as a defence mechanism.

Gutting the cats leaves them visually intact if you have to contend with inspections. However, you have to be extra thorough if you have rearmount turbos.

Even if you dont currently have inspections, it might be a good idea to replace with a pipe and keep them just in case. Because, you know, global warming....

Dave concrete

10 year old Cats just checked, and are perfect. Tuner says Cat problems more of an issue with high boost cars, not low boost.

_zebra

high vs low boost are relative terms...
you talking to the causal weekend warrior or somebody who runs TX2K? compression ratios? gas or diesel?

Dave concrete

Post #3 would have answered the question. But my car is weekend warrior, it sees 6-7 psi and is just shy of 600whp. I'm the type who refers to the tuner. My job is concrete/Masonry, his job, very well known, is a vette tuner who majority of the business is blown cars. He could have sold me anything he wanted because I didn't have a budget nor did I question . Now, in the defense of all sides, I was asked my goals, my future, and what I want, so with that said, Cats were put on.

_zebra

yeah, i get what you mean. i was just saying that boost level being high or low depends on more factors than a psi reading when applying this advice to different setups. the casual driver might consider 10psi a bunch, but somebody building an all-out beast might not take anything under 15psi seriously. 8psi on pump gas with 11:1 CR is effectively a bit "higher" boost in this sense than 12psi on E85 & 9.5 CR. cam comes into play, too. and, as evidenced here, different people have different opinions/experiences on where the cut-off point is, too.

i ran ARH's cats on mine at ~530whp for 7yrs @ 10psi on a stock LS1 & never once had a problem (still looked good when i punched them). in deciding whether or not to ditch mine with this next round (shooting for +100hp), the biggest recommendation from multiple sources was to remove them due to the significantly-increased likelihood of failure around the 600+ mark... even with a good tune. some guys reported running 600-700hp for a good while before failing on more-involved car builds. some reports were from dudes having them fail on stock LSAs shortly after a pulley swap for mid 500s. my well-known tuner highly suggested i get rid of mine, and i figured in my absence of inspections, it's easier to not chance it. i just wanted to present info for others to consider when reading through this - that's all.

materials, density, & build quality of the catalysts themselves also play into longevity. yours could even end up working flawlessly for all i know.