With the lack of ability to simulate the O2 sensors on the '13+ headers, I'm ditching the header upgrade and just going with the URD y-pipe. That said, I'd like to ask people here how difficult of an install this is. It would seem rather straight-forward, like I could just crawl under the vehicle and do this in an hour or so...



But then there's always the possibility that there's loads of head shields, bolts, and other things that need to come off first. Who has done this, and what was your experience?

If it's simple, I'll order it pronto before my move to Colorado. If it's a lengthy job, I'll just wait until I get there and use my buddies lift. Thanks!

Not difficult if you don’t have rusty bolts. Check them and/or start spraying them with Liquid Wrench. The toughest part would be snaking the Y-pipe out because of the size of the catalytic converters. You know you can install the headers and add O2 sensor extensions which will eliminate the CEL. But you’ll have horrible & deadly fumes if you remove all 4 cats.

Ok I think I'm confused about how many O2 sensors there are...

-It appears there are 2 sensors at the top of the y-pipe (side closest to the engine).
-There are 2 sensors after the stock cats on the headers. This is what causes the trouble on the 13+ units.
-Are there an additional 2 sensors pre-header-cats?

Also, why on Earth are there 2 sensors post-header-cat, and 2 sensors pre-y-pipe-cats? Those seem completely redundant...!

Anyway, if I replace the headers (but not the y-pipe), what would the extender do for me? Would I have to drill extra O2 ports on the stock y-pipe post cats?

There’s pre and post O2s for the ECU to calculate fuel mixtures. You’ll need the O2 extensions on the post cat O2 sensors, if you remove the 1st set of cats at the headers. I’m not familiar with the newer V6 headers. Are the Cats welded onto the OEM exhaust manifold or bolted up to them?

The cats are part of the headers. I was wanting to go with long-tube headers which delete the header cats, but you can't simulate the rear O2 sensors in the 13+ units like you could with earlier units.

I just re-checked some pics of the headers, and there are indeed pre-cat ports (on the headers), and post-header-cat ports (on the y-pipe). There are no ports post-y-pipe-cat.

So total of 4 O2 sensors. I still don't understand what the extender does for you. Where would you hope to place the rear O2 sensors such that you could avoid the CEL? It seems you'd have to drill your own ports post-y-pipe-cat.

All this trouble with the headers is why I wanted to go with the y-pipe instead. I'll be leaving the stock headers (and cats) in place. I'd rather delete the header cats, and replace the y-pipe with high-flow cats, but that's not an option...

As far as the Y pipe goes it is a super easy install. Only Issue I had was the need to drill out the flange holes a bit on the new pipe.

I did not really install it for power gains. the big advantage of it for me was clearance. The crossover hangs down low and forces any type of skid plate to also be low... hurting break-over angle offroad. But there is obviously a little performance gain.

For the headers.. they may include an extension harness for the WB o2 (primary) sensors since they would sit further back. The secondary sensors would be useless and there would be no point in using them as they would simply set a CEL all the time without the cats in place. You would be better off just plugging the holes for them with a plug.

Being how mine is an 11' , very easy crawled underneath saw where o2s were & got the 22mm sensor tool wrench took them off & sprayed the crap with Pb blaster came back 1/2 hr & started unbolting ! Took me an hr . Have not f-d with upstream a/f sensors ! Simple 2 on the scale !

as far as the sensors i was told by gadget that i wouldn't have any issues installing my long tube headers and adding my y pipe and hi tuck exhaust. i asked about an 02 simulator and he said it wasnt needed. now im kinda frustrated as ive been going back and forth with him and don't want to run into any issues doing this install

What year is your vehicle?

jus got back word it will now which frustrates me because i wouldn't of ordered the y pipe and exhaust

Yeah... You should still be OK with the y-pipe and exhaust though. The long tube headers are the only thing that causes a problem. Gadget informed me that the O2 simulator was under development, but there's no ETA.

how does it sound? factory rear exhaust section? contemplating this as well but don't want the drone as its my daily

Curious how this sounds and if there is any actual performance improvement when keeping the OEM exhaust beyond the y pipe.

Removing the 2 cats in the y-pipe is definitely going to improve the performance a bit. I highly doubt there would be any noticeable sound difference if you keep the stock muffler.

For a reference point, I replaced the headers, up-pipe, and downpipe on my '05 Subaru Legacy GT (turbo 2.5L), and kept the stock cat-back. Zero noise difference from within the cab. However, I was getting a lot more power because 3 OEM cats were replaced with 1 high-flow cat, and the new headers spooled the turbo faster.

Anyway... it's not ideal leaving the final restriction (OEM muffler) in place, but by the time the gases have gotten to the muffler, they've cooled a little and the pressure is down a bit. I'm going to try the y-pipe-only method and see how it goes. If there's an appreciable seat-dyno difference, I'll report it (or mpg difference).

Would be interested in hearing what the sound increase is. I went to a URD Cat-System. Little to no noise increase around town. On the road, it is louder without any drone. I would think with the Y-Pipe and eliminating rear Cats would see additional sound.