Just wondering how much difference a high flow cat would make on performance in my 01 cherokee. Is it worth the money and trouble and will it cause OBD codes ?

 

not worth it to me. and i've seen a lot of aftermarket cats cause codes, even if they say obd2 compliant. i'd spend my money elsewhere.

 

Thats what I was thinking so Im glad to here it from someone else. I think I will just replace the muffler with a dynomax and call it a exhaust system !

 

OEM cats are pretty restrictive.

 

its probably more appealing to younger guys, i've outgrown throwing my money at that. and its not worth the hassle if you get one that starts causing emissions problems. i'd put the money elsewhere. if you wanna feel better power get some gears, build a stroker, thats what you will really notice.

everything else is in the same category to me. chips, cold air intakes, tb spacers, bored tb, exhaust and so on.

horespower numbers are all so inflated and over rated these days, every thing gives you more horsepower. most of it isn't really noticeable except for whats in your head. thats all i say. a new cat will give you more horsies, its just not something i focus on anymore.

 

they will rrestrict less but if u call a tech line they sasy dont use them cause they throw engine codes all the time

 

I had a high performance cat installed on my '97 ZJ w/5.2 over a year ago at my friends exhaust shop. Both O2 sensors were retained. No other changes were made at the time. It passed the AET test and hasn't set any codes yet. I could definitely hear and feel the difference right away.

 

I do agree to a certain degree on ODBII jeeps but on oler ODBI you're not going to get any codes since the only O2 is pre-cat. Also on that list I agree with you 100% except with the bored TB, it won't add noticable HP but is more of a throttle response and if you have the tools to do it then it's worth the effort. To me it simple makes better use of the HP you have.

 

i don't see it being a necessary item for wheeling so i don't bother. if you want a sports car buy something else

 

all true, obd1 won't have an issue, and the bored throttle body is about the only one of that list i may due.

 

i got a high flow flowmaster cat and a straight through s type flowmaster muffler, it sounds ok not loud just throuty, but the cat was like a fourth of the size of the OEM cat, i only bout that stuff cuz it was so cheap were i work.

 

idk what you're smoking, but any legit cat (i.e., not a test pipe) wont throw a code, on any car.

 

i guess i'm smoking years of experience, and redoing the cheap "valesquez muffler shop" cats, and aftermarket "performance" cats, cuz they won't pass emissions, and thorwing codes.

i've made a ton of money off people putting that stuff on their cars. even the aftermarkets that say obd2 compliant can cause problems. then the customers are pissed cuz they spent a bunch of money on something that has to be redone.

 

back in the day sure, newer stuff... not so much. using 30 dollar ebay specials will cause an issue, but any legit brand one wont. im running an ebay hi flow universal mini cat, and the same one is on a couple of my friend's jeeps with OBDII and there are 0 issues. after cat 02s are dumb anyway.