idealrides

I was looking for this for a while, and though others might need it to get rid of the check engine light.<ul><li><a href="http://www.motorsporttech.com/impala/exhaust.html">http://www.motorsporttech.com/impala/exhaust.html</a></li></ul>

Cup-a-Chow

And $99 is steep for 02 simms. I can get a hookup from my old car club on those for ~$70 each. If anyone can take a pic of the 02 connectors I can tell you if they will fit or not.

eharleq

That will go well with the Federal offence for tampering ; )

Dr. Mike

Hi,

I don't believe this part is even necessary. The primary job of the O2 sensor in most cars is to keep tabs on the air-fuel mix. Why not just run a test-pipe and save the $99.00 (I did this on my 96 Integra GS-R for a series of track events and never saw a check engine light).

As most have pointed out here, modern cats are not a major source of restriction, and if you absolutely must have that 1-2hp, get an available high-flow unit.

This restrictive cat myth dates from the 1970s when they were no more than metal boxes with the catalyst bound to the surface of basically a gravel-like substance.

If you really want to work on a major restriction go for the MAF sensor, in many recent model autos it puts a ceiling on what a high flow intake will get you. The Mazda built six for the Probe/MX-6 is a prime example.

Cheers,

Michael

Cup-a-Chow

Removing the cats will give you a couple HP, but nothing phenomenal. At least on NA cars. Maybe with turbo cars you'll feel a bit more.
But since OBDII was introduced, nearly every single manufacturer has an O2 sensor behind the cats for the sole purpose of making sure they are there. If you take a cat out, the O2's will sense the change and throw a code. Or at least most cars do, but I'm not sure if it's all like that. The only reason to have those is to not have a code set off on your dash.

If I'm correct, rich / lean O2 readings come from the O2's before the cats, not after. So these O2 simms just trick the computer into thinking that the cats are still there.

CharlieGSanD

<center><img src="http://pictureposter.audiworld.com/8383/dsc00037.jpg"></center><p>i recently installed a high flow cat and saw a decent improvement 15-20 hp

CharlieGSanD

<center><img src="http://pictureposter.audiworld.com/8383/dsc00042.jpg"></center><p>

Dr. Mike

Hi,

I agree that an aftermarket cat will flow better, I just find it difficult to believe its on the order of 20hp. You also have (a very nice car!) a larger turbo than most of those here who want to ditch (not replace with a better unit, as you have) the catalytic converter in the quest for more power. A restriction becomes a greater concern proportional to the amount of stuff you are trying to push through it. So if you are seeing 15-20hp and have twice the exhuast volume (high boost &gt;15-20psi), the mild mannered motor with the K03/04 will only see half the gain, if that.
I still don't think it is worth ditching the cat. The best alternative is what you have done and get a good low restriction model, and keep legal.
On that note where did you get your hi-flow unit? ;-)
Cheers!

Michael

Cup-a-Chow

Looks like quite a difference between the two. 15-20HP... is that on a dyno? I've been looking around for a 4 wheel dyno ANYWHERE around here in CA, can't seem to locate one anywhere though... Not sure if there is one.

CharlieGSanD

but i did the FMIC at the same time so i cant say for shure which gave more power.

but the turbo spools MUCH faster

i say 15-20 because if the chip was 45, this was about 1/2 of the diffirence i felt whith the chip

i got the cat at Evolution motorsports--EVOms.com