In another thread I was asking about the way my car was shifting - especially pulling a hill - and Mike (ChibiBlackSheep) made mention that the problem may be related to a bad cat converter. I took my car to a friends' shop and found that engine vacuum was dropping off and erratic above 2000 rpm. There was also a noticable difference in exhaust pressure pre versus post cat. Sure enough, the cat is plugging up. So, I went over to eBay earlier this morning and started looking around in the exhaust section. I came across a Magnaflow downpipe with cat and u-bend delete that was at $71 with only a couple minutes left. Just for grins I threw a bid at it and won! It's being delivered to my door for $100! A Thank You goes out to Mike for his insight and willingness to share his knowledge and experience!

 

Any time!

Hopefully this aftermarket cat is a good replacement and doesn't go bad. Remember you will most likely get the P0420 code now and then you'll start looking into tuned PCMs or O2 sensor fakes

If you are due for inspection soon, I would wait to put it on.

 

It's the Magnaflow 23405 so I'm hoping it won't be troublesome. They say it's a direct fit and designed to OE spec, but I guess that's no guarantee it won't end up throwing a code. I don't have a smog check due until April of '13 so that gives me a little bit of time to resolve the P0420 problem if it does arise. I also read your post about the AC Delco O2 sensors at Amazon. The one for my vehicle is around $45 so I'll probably toss a new one into the downpipe prior to installation. From past experience with them seizing it will be worth it versus the cussing and bloody knuckles when the old one snaps off at the base.

 

Since you are replacing the whole downpipe assembly make sure the inside metal is clean before you install it so you don't foul out the brand new o2 sensor lol

 

The downpipe is NIB, but I'll hook a shop rag soaked in acetone to a wire and run through it to make sure there's no oil residue from shipping in it.

 

FYI - If the car DOES throw that P0420 code, a trick I was looking into when i first put a high flow cat on my Monte was a spark plug anti-fouler. The concept is to space the O2 sensor out of the main exhaust stream, reducing what exactly it receives for readings. I've read people with multiple different drive trains that claim success using that trick (I also know someone personally that had a VW he put a aftermarket replacement cat, non-high flow and had to use that trick to get past that code).
I got lucky and never had to use that trick, and since I had my PCM tuned, I had that code deleted from it at that time.

 

Not just oil, but a fine powder usually is inside new exhaust components.

 

I'm glad i live in iowa for once so i dont have to go through an emissions test

 

Yeah, I did not do any internal cleaning of my down pipe (but when I looked in it, it seemed perfectly clean).

But in the case of my ZZP Power Log, I saw a powdery substance in there, blew it out with the air compressor.... Shame on me, I should have done more cleaning.... End result, i did destroy my upstream O2 sensor as a result. DOH!

Live and learn.