Catalytic converter question

[ajflan]

Ok, I am FINALLY about to install my 2 1/4" midpipe. However, I do have a question I hope someone will be able to answer. As seen in the picture below, the stock exhaust has what looks like two cats. Now, I know that one isn't a regular catalytic converter. I am thinking about taking off one of those, but I don't know which one to take off. And if I take one off, will I get a cel? And before all of you start telling me how loud and ricey it will be (especially since I don't have a resonator), I just want to say that there is nothing you can do about it. I would greatly appreciate any help in creating the loudest Vibe here. (Its kind of an experiment, I can always tone it down later.)(This is the JP midpipe, I am just using the pic for comparison)

[kevera]

I thought you already used the mid-pipe.Most people take the first cat out(pre-cat),or hollow it out.Why don't you just use that mid-pipe then,if you haven't used it already.

[drunkenmaxx]

ha yours wont be the loudest, that guy that has the pipe that dumps off right after the cat has that title for sure!

[Petrucci914]

If you'll be removing one then you'll want to remove the second one, as there is no O2 sensor after it. If you remove the first one then the second O2 sensor will give a bad reading and you'll get a CEL. I plan on ditching the second one and replacing the first with a Magnaflow Pre-cat which can be had for around $60 on ebay.

[northvibe]

all these cats and backs...and pipes confuse me..looks like ill just throw on a straight pipe

[Petrucci914]

If you wanna sound like you have a truck with glass-packs, go for it

[northvibe]

hahah only if i had 2 1zz's in my car so it would be a v8 technically wait ok so I get a magnaflow cat back system, then I still need a mid pipe and down pipe?

[Petrucci914]

Ok. You have your exhaust manifold/header. That has an O2 sensor in it. Then that goes to a precat and there's an O2 sensor after that. After that O2 sensor is the post-cat, then a resonator, then that goes back to the muffler.When you get a header that replaces the exhaust manifold. If you get a Magnaflow Catback that does what it says, replaces everything after the post-cat. So on my vibe I still have the two OE catalytic converters. I will be replacing these. If you get a JP Mid pipe it'll replace everything from the header to the muffler, then you have to buy a muffler to hook to it.

[northvibe]

well i have a stock exhaust manifold to get ported. So if i got a magnaflow cat back system id just need a down pipe?

[Petrucci914]

Not sure what is all contained in a downpipe, but I believe you're correct. The space between the exhaust manifold and cat-back system would have to be replaced. That'd have to be a custom job as there is no aftermarket replacement for that. To do it all aftermarket you'd need the header, then the JP midpipe and have that go to the Borla system which is JUST axleback. If you got the JP midpipe and Magnaflow catback you'd have extra piping.

[Kamikaze]

they couldn't have made this any easier could they...

[Petrucci914]

hehe. It's not too bad. The catback is the best way to go and then doing a custom 'downpipe'. Last time I checked, the JP Midpipe was like $700, so unless I sell a kidney, it isn't happening. A magnaflow cat can be had for like $60 on ebay, then pay some dude to weld it up with some new piping to the magnaflow.....won't be too much. I can't wait to do it.

[northvibe]

JP makes a down pipe too, and i think thats all thats needed if you have a cat back. mmm for full exhuast its like 1000 dollas

[Petrucci914]

Eh, screw JP. Overpriced crap.

[ajflan]

Quote, originally posted by kevera »I thought you already used the mid-pipe.Most people take the first cat out(pre-cat),or hollow it out.Why don't you just use that mid-pipe then,if you haven't used it already.Things got a little complicated. My buddy who built the midpipe and was going to install it found out that he has cancer, so everything was put on temporary hiatus. So if I take out the pre-cat, will I get any CEL?

[Petrucci914]

Definetely a CEL. The O2 sensor will get an out of range reading.

[ajflan]

So I cant remove either without getting a CEL then.

[Petrucci914]

Not unless you get one of those things to trick the O2 sensor into thinking everything is a-ok. Never used one and don't know how they work. I'd just replace the pre-cat and remove the second.

[kevera]

Hollow the pre-cat and put this on.http://www.voodooboost.com/per...ator/

[ajflan]

Thanks Kevera.

[satur9]

i have the jp headers and midpipe and thermal r&D exhaust.it removes the first cat and puts the o2 sensor after the 1 cat thats left essentially. anyway. if you wanna do it right put in one cat and a o2 bung after it with a mechanical(pipe extension)not electrical o2 sensor tricker.the mechanical ones just space the o2 sensor farther out but still samples the exhaust. but the electrical ones dont and while you may not get a cel. most of them dont send a ready signal to the obd2 so you wont pass emisions if you state has them.i have the weapon-r cel one.but thats because clearence is tight on the jp midpipe. depeding on where you put the cat the cheaper ebay ones my work.

[kevera]

When Ajflan brought this up,I was wondering who had a loud Vibe.Now I remember it was you Saturn.Your Vibe sounded wicked.Ajflan,it will be a toss up between you and Saturn then,if you go through with it.

[ajflan]

Quote, originally posted by kevera »When Ajflan brought this up,I was wondering who had a loud Vibe.Now I remember it was you Saturn.Your Vibe sounded wicked.Ajflan,it will be a toss up between you and Saturn then,if you go through with it. It will be close, but doesn't the JP midpipe have a couple long resonators on it?

[Lancer]

Quote, originally posted by ajflan »Things got a little complicated. My buddy who built the midpipe and was going to install it found out that he has cancer, so everything was put on temporary hiatus. So if I take out the pre-cat, will I get any CEL?Sorry 'bout your buddy.Yes you'll get a cell, but it wont effect anything. Just have an anoiying yellow light on all the time. And if something else were to go wrong with your engine, you wont notice the new cell.I had, and still use and extender for my second O2 sensor. I can't think of the name for the parts I used. something like spark plug gapper or something like that. From Autozone. You have to drill out the bottem of the one that the sensor goes into. It sorta worked when I had no real cat. I'd get a cel for a day or two, then it would go away.Quote, originally posted by kevera »When Ajflan brought this up,I was wondering who had a loud Vibe.Now I remember it was you Saturn.Your Vibe sounded wicked.Ajflan,it will be a toss up between you and Saturn then,if you go through with it. I'm gonna claim the "Loudest Vibe" title. 3" stainless steel from D/C sports header to tip with a magnaflow race cat (really short!), magnaflow resonator (4" X 15"), Magnaflow oval muffler (POS). Stuck a couple cones in the tubing and the exhaust tip to help quiet it down a little (removable ). Gonna try a HUGE Aero exhaust muffler when I have the money, after the new engine.

[ajflan]

Ok, loudest naturally aspirated vibe.

[satur9]

sorry but my vibe wasnt that loud .the 2zz with no muffler was louder.spark plug antifoulers is the autozone part i guess they work better on high flow cats than no cats.cause i dont get a cel.