Yea , I posted the links here before on a different thread . The debate was over removing the cat and performance differences . That's a few yrs back . That report had actual dyno numbers . I did my searching , you find it . I've already been through this .
Have you ever seen the inside of both a stock and a high-flow cat . In case you have not , and for others , let me explain . A stock cat is crammed full of catalyst . Recycling it yields $50 because it contains so much . Magna Flow , which I have seen inside of as well , consists of two 1/2-3/4" slices of catalyst on each end of the cat where the in/out openings are . You can see through them , the stock you will not see even a glimmer of light . Recyclers won't pay $0.05 for a Magna-Flow cat out of the box new .
Let's define "high flow" . Shall we say something that flows high than the normal rate ? Sounds close enough to me . What part of understanding that the term high flow applies to these cats do you not understand ? These HF cats are almost like a straight pipe because the have such little restriction
Fact : less restriction = more hp , regardless of how much , there will be an increase . If not true , there would be no reason for hearing protection at a drag strip .
Even replacing a stock cat with a direct fit high flow cat will get more power on the dyno . Most go with a bigger diameter on the outlet side only because stock reduces it down 1/4" right there for absolutely no apparent reason , on all ZJ's . Accompanying that would be a new muffler to match the new inlet dimension as most will opt to do at this time . You still retain the same cat inlet , and muffler outlet dimensions .
Where is all this "extra " money for a HF cat ??? I pay $67 for a Magna-Flow with free delivery . I get $50 for my old stock unit . Cat cost is $17 .
Ok , this is going way off topic here . Start your own thread and start the debate there . Get more than one biased article before you do