friend has I/H/E on a B7 in a hatch, and wants to buy a high flo cat. which ones are better, the ones that are skinny that looks like a pipe or the ones that are fatter?

 

whichever one that has better flow.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civiccoupe94 &raquo;</TD></TR><TR><TD CLASS="quote">friend has I/H/E on a B7 in a hatch, and wants to buy a high flo cat. which ones are better, the ones that are skinny that looks like a pipe or the ones that are fatter? </TD></TR></TABLE>
The cat ignites and burns the remaining gases from your exhaust, and the o2 sensor takes its reading from there to adjust the air/fuel mixture. If the cat isn't working properly or is replaced with something that isn't as efficient (testpipe) the sensor gets fouled up. This will make your mixture progressively more rich. Basically, unless you're changing the sensor on a regular basis, the minimal power gains you receive by deleting the cat are more than lost by your pig rich fuel mixture. Plus it'll sound shitty and stink. Unless you're requiring more airflow (FI), it isn't worth it.

I don't have any experience personally with any testpipes or highflow cats, but if your buddy is buying one anyway I would find the cat that still does its primary job. This is also important when smog check comes around if you have it. I live in the land of eternal winter (canada) so this isn't an issue with me (Other benefits car-wise are: turboing my car isn't illegal, and any car can be imported from any country as long as it is 15 years or older.)

 

well if he's got a b7, as in d15b7, the car is obd1 and only has 1 o2 sensor which is pre-cat. so its not going to foul the the sensor if he runs a testpipe or hiflow cat. have him get whatever he can find for a good deal. either one isnt going to help in gaining much power until he boosts the car.

 

BOOOO.. BOOOO to high flow cats. jk, i just dont like the noise, not much gain either, and if your state has inspections (which most will sooner or later) you prolly wont pass (depending on ecu)

 

Your ECU isn't going to like the hi-flow cat, and the gains are minimal. I'd just stick with the factory cat if I were you.

 

i have a magnaflow high flow cat.. works great on a stock b7

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95dxhatch &raquo;</TD></TR><TR><TD CLASS="quote">well if he's got a b7, as in d15b7, the car is obd1 and only has 1 o2 sensor which is pre-cat. so its not going to foul the the sensor if he runs a testpipe or hiflow cat. have him get whatever he can find for a good deal. either one isnt going to help in gaining much power until he boosts the car. </TD></TR></TABLE>
good point

 

i was thinking of getting one also. i see some of you guys say the it sounds diff. does it make it sound ricey or what????? please let me know . thanks in advance

 

as long as you have a good muffler, cat won't affect the sound THAT much... now if you have a straight through muffler (basically a resonator) then it will make it noticably louder

 

I just got the Magnaflow Carsound Cat off of Ebay and it sounds great & it works!

 

I have a straight through style cat and I honestly can't stand the sound. It is coming through an Edelbrock proflow header and 2.5 back to a Megan muffler. Entirely too loud. I am going Mugen shopping just to quite the car down as everyone and there mother revs at me trying to get me to race because the car sounds so damn ricey.

 

thanks for the replies guys.. he just bought the fat one, that looks like the size of a OEm cat, not the test pipe kind. i'll post the results on it once i help him put it on (loudness of the muffler, power gains noticable, etc)

 

and yes its a OBD-1, so only 1 sensor at the header part, no sensors from there on all the way thru the muffler.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civiccoupe94 &raquo;</TD></TR><TR><TD CLASS="quote">and yes its a OBD-1, so only 1 sensor at the header part, no sensors from there on all the way thru the muffler. </TD></TR></TABLE>

therefore no sensors will be affected nor will the ecu.....not sure what some of you were thinking when you replied. it would if it were obd2 but its not. good luck with the install. time for boost next

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civiccoupe94 &raquo;</TD></TR><TR><TD CLASS="quote">friend has I/H/E on a B7 in a hatch, and wants to buy a high flo cat. which ones are better, the ones that are skinny that looks like a pipe or the ones that are fatter? </TD></TR></TABLE>

or wait....maybe i should quote all of you f*cktards on this thread...about 95% of you have no f*cking clue what youre talking about...with all your obd and high flo jargon...that high flo cat is gonna give your low flo bank account a reaming..and leave you with one more hp totaling your suckmobile to 103 at the crank...geez move over ferrari here comes the steam...why did he even waste money on that engine...man im so sick and tired of hearing about you idiots that can justify spending 1600 dollars in bolt ons instead of buying at least a b16...but if you really want your "high flo" since your friend drives the fire-breathing d15b7 you should just hollow out your cat for free....or you better make sure that high flo deal is emissons legal...or else you wasted 100 bucks that you couldve saved for something thats actually fast

 

And you are angry because? Dude get over it, if he wants to put a high flow on his lawn mower, so be it. Just be here to answer his questions about whatever he has and leave it at that. If you are a motor swap guy, so be it. No reason to damn everyone who decided to mod the stock motor vice spend 3k to go DOHC VTEC.

 

good point...but the dohc swap can be had for even half of that figure...im just saying that it makes absolutely no sense to spend that amount on something that will not amount to much

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by transpar_nt &raquo;</TD></TR><TR><TD CLASS="quote">The cat ignites and burns the remaining gases from your exhaust, and the o2 sensor takes its reading from there to adjust the air/fuel mixture. If the cat isn't working properly or is replaced with something that isn't as efficient (testpipe) the sensor gets fouled up. This will make your mixture progressively more rich. Basically, unless you're changing the sensor on a regular basis, the minimal power gains you receive by deleting the cat are more than lost by your pig rich fuel mixture. Plus it'll sound shitty and stink. Unless you're requiring more airflow (FI), it isn't worth it.

I don't have any experience personally with any testpipes or highflow cats, but if your buddy is buying one anyway I would find the cat that still does its primary job. This is also important when smog check comes around if you have it. I live in the land of eternal winter (canada) so this isn't an issue with me (Other benefits car-wise are: turboing my car isn't illegal, and any car can be imported from any country as long as it is 15 years or older.)</TD></TR></TABLE>


From the research I've done before I got my High flow cat, I came to know that performance is affected if the 02 sensor isn't getting a good reading (from the cat)

I personally have a 2.5" carsound high flow cat, got it because I put on a JDM DC header and the stock cat wouldn't fit it anymore. I even had the shop put the 02 bung in it, after a while though the cat burnt out, obviously due to the car running rich, since stock Si's (b16) and GSR's (B18c) run pig rich from the factory anyways, the check engine light came on. There was absolutely no difference in performance.

Gas mileage has been the same, as if the car were stock if I drive normally. There was a dramatic increase in performance, noticibely in high end, but I think that was mostly due to the header since it has the 2.5" collector. Although a somewhat 'gutted' cat (burnt out all the catalyst) helps.

The sound however isn't anything to write home about. While it's not that bad, has gotten really loud. I have a Greddy Evo exhaust, and I remember it being pretty quiet before I put the JDM header with the highflow cat.

If I had to do it all over again, I would just get a test pipe and call it a day.But then again, my check engine light turned off on it's own, so probably the o2 sensor is burnt out from too much heat/carbon deposits/dunno. Anyways, don't really have any complaints.

P.S. Didn't pass smog with that setup either. Although the tech didn't really notice the lack of a carb # on the header, it did not pass the sniffer test. DUH~


Cliff notes: Just get a b16.