CTS catted-downpipe STINKS! (literally)

[danbfree]

I know, reviving a zombie thread, but some good info to know who may be looking, like I have myself, is that the CTS is unique with its O2 sensor port *above* the cat, so it will be just as challenging to get a spacer just right as running completely catless... All other catted DP's I know of have the cat in the stock location, and O2 port past that, so much less smell at startup with faster warmup and less residual smell even once warmed up as it gets heat from the engine constantly to keep it hot and efficient. Also, with the O2 sensor and spacer should be much easier to pass emissions.

 

[jimlloyd40]

Okay ya this is a mad old post and I assume you figured your situation out but, Bro I know what you need to make you sleep at night again. Get a straight spacer, it solved my problem immediately on my Unitronic Downpipe. As you said, Unitronic downpipe will give you a near immediate CEL. It doesn't play games with that. The J spacer that @El_bigote_AJ mentioned above will work with the CTS downpipe, but won't clear your Unitronic Downpipe - so you yourself need a straight spacer, not that J shape. I am telling you after having experience with both. Get one from online or get a used one for all I care. Or make one, which I failed at trying to do!

Like I said, fixed my CEL immediately. Just install the straight spacer, clear your codes, and drive until your accessport shows readiness across the board. You shouldn't ever see that CEL again and can run that Unitronic downpipe with or without a tune. And you are golden my boy.

Except the guy you quoted hasn't been in the forum since June of this year. Before you respond to someone on an older thread click on their avatar and it will tell you when they were last in the forum.

 

[SmoothCat565]

Except the guy you quoted hasn't been in the forum since June of this year. Before you respond to someone on an older thread click on their avatar and it will tell you when they were last in the forum.

You sound like you're trying to help me, and for that I appreciate you mentioning it. But I said in the first sentence of my post that I know it's been awhile since that guy posted. I replied anyways because I think it's useful information to have out there, not necessarily for him, but for anyone else trying to run a Unitronic downpipe.

 

[GTIMK7inCT]

Here’s a cut and paste of a review I posted on the ECS Tuning website that details my experience with the CTS high flow catted downpipe and its smell.

Good Product with Some Considerations

The quality of construction of this downpipe is quite good and installation is not difficult. The toughest part of the job is removing the OEM downpipe because it’s tricky to wriggle it out due to its snaky shape and the size of the OEM catalytic converter. Despite a seemingly tight fit of the sections and rather robust clamps I did have exhaust leaks and a CEL immediately appeared. I had to entirely remove the CTS downpipe, replace the OEM exhaust gasket and clamp at the downpipe and turbo outlet junction. In retrospect, I don’t believe this was necessary as my GTI had less than 20,000 miles and those parts were in solid shape. However, both parts are inexpensive, so why not? I also spread Accousti/Seal sealing compound between every joint of the CTS downpipe system. This solved the exhaust leaks but the CEL still lit up despite the fact that I had installed the high flow catted version of this product. Thus, I also purchased and installed an O2 sensor CEL fix and that solved all problems without the necessity of a Stage 2 tune. Nonetheless, I have to mention that without any exhaust leaks whatsoever, this catalytic converter still stinks! Within seconds after starting the car the garage smells horribly. And if the car is at a standstill with the engine running, the cabin is flooded with a toxic smell unless the air flow is set to recirculate. These problems are well noted on many reviews online. I have read that the cat smell dissipates as more miles are put on the vehicle. I have not reached that point yet, though it does seem the odor is lessening.

 

[ctrldel]

Can confirm, the catted CTS downpipe isn't that great for cutting down smell.

Even if 100% properly installed and sealed up, it still will smell like you describe.
The high flow cat + the position of it being further back means it doesn't get to proper operating temp very quickly if at all, so it's not all that efficient as a catalyst.

It was one of the big reasons I moved to an IE downpipe. The cat in the factory location gets a lot more exhaust heat.

So i know this post is old but after moving from CTS to IE did you find a very noticeable improvement?