Has anyone tried the magnaflow oem-grade y-pipe for the V8? Based on the one thread I have found here (for a different style of y-pipe) they look to have good (potentially mandrel) bends, not crushed. They use a real Y merge and are probably 409 stainless. Parts are 49698 and 49697.

I’ve got long tube headers coming, and I’m thinking these may be a better choice than the DT or URD y-pipes (for me, at least) since they’re still retaining some oem-grade catalytic converters.

I’m not in an emissions area, but I’m also not interested in the environmental impact of fully straight-piping. I had looked at getting the DT y-pipe and cutting out the resonators and having a shop put some cats in there instead, but then I realized in not really paying for anything better than the magnaflow unit at that point.

What’s weird to me is that I just haven’t seen ANYONE mention these here, and a lot of us seem to want to upgrade the Y-pipe with the exhaust manifolds to headers upgrade. Aside from the set being ~$800 for the oem grade, I feel like I must be missing something.

Maybe those Cats are too far back to heat up effectively and don’t really help Emissions much, or maybe it’s because there’s not a monitor there, so these cats have no impact on CEL status (therefore nobody cares).

Any thoughts?

Nah. Get the Doug Thorley Y-pipe.

I’m not really jazzed about not running any catalytic converters in my daily driver though.

The extra emissions and the smell...

I placed my order for the Doug Thorley long tubes today and ive come to a conclusion im just going to leave the stock y pipe and cat back in for now and just bolt the long tubes up. I may have something fabbed up with high flow cats eventually for the smells and backpressure, but for now staying oem ypipe back

Hey i got my long tubes headers from urd and i guess you got your already on did you had any problems with o2 sensors when i order mine urd hook me up with o2 simulators and also did you fab anything fit them right or just slap them right on

I was thinking about these magnaflows too at one point to help with the smell of running no cats. Just my personal preference - I have the LT's and URD Y-Pipe installed currently and luckily no emissions testing in my area but they do get stinky if you're driving with the windows down. Windows up is no problem. If you get them, I would love to hear how they perform.

I'm trying to research as much as I can about catalytic converters to see how things might shake out. It does seem like the temperature of the cat has a direct correlation with its filtering ability - and, in turn, the smell. The rear cats on my 4runner are about 300 degrees cooler than the fronts at all times, according to my Bluetooth OBDII tool. I'm wondering if maybe some heat wrap on the y-pipe before the cats would keep the temps a little closer to what my fronts are running and if that would help with the smell. I'd try to figure out a shield or a just run a skid plate to keep the wraps from getting wet and all those issues I've read about them causing the pipes to rust away. I'm probably just overcomplicating things even looking at heat wrap...

I'm also reading that another part of the rotten egg smell may be from running a little too rich. I'm not too far down that rabbit hole just yet though.

I've heard the grade of fuel can determine the sulfur smell as well.

I've heard the same. Apparently the fuel restrictions are so tight in Cali that there isn't a smell there to begin with..

Here in North Georgia, I'm kind of SOL. I've run everything from the cheapest 87 octane ethanol blend to 93 octane 100% gasoline for a few sequential tanks at each level with no noticeable impact to smell.

Most of what I've seen is sudden spikes in throttle where the cats are running at like 1200 then spike to 1600 is when I get the smell. It would make sense that I'm just overloading the cats momentarily. Long grades will also do it, so I'm just not sure if it's a single cause or the smell occurs at different times and for different reasons. Could be running rich on long grades and overloading the cats on heavy throttle, etc.

When I changed my spark plugs, I noticed a decent reduction in fumes as well. I haven't tried higher grade fuel since I did the plugs, now that I think about it.

The main thing is that I'm already in process of getting long tubes. I bought the premium ones that should be another 5-7 weeks from shipping. So, I know I'm going to be reducing my ability to control the exhaust fumes from the elimination of the primary cats. I'm not going full straight pipe. I'd leave on the stock y-pipe before I'd do that, so I'm really narrowing it down to keeping stock, getting the magnaflow y-pipe, or finding a place to weld up a set in stainless for me.

Oh, You've got the Dirty Deeds exhaust I was looking at! How much did the 20" with the Helmholtz run you? I was looking at your build thread and that whole piece - flange to flange - is exactly what I was looking for. I might go with the 24", but other than that, it's spot on. I'm not looking for loud, just better breathing.

$750 I think, so not the cheapest but I have no regrets. It's stainless and fricken heavy. Sounds awesome but I would go with the longer muffler since you'll be removing some cats and still want it quiet. My 20" with rear cats removed and rear resonator removed is moderately loud.

I'm gearing up to build y-pipes and full exhaust systems potentially from tig welded 304 stainless but I'm not sure when I'll get to it with winter closing in. Haven't planned, measured, or tested anything at this point. Keep an eye on my build thread for updates.

Good to know. I'm still waiting to here back from Keith, so at least I've got a better idea now. If your plans involve replacing your DD setup, I'd buy it off you in a heartbeat. I'll just leave on my resonator and hope for the best, lol.

.. Really interested to see what you can come up with, though. In my mind it would be super cool to run a short cat RIGHT AT THE FLANGE (best I've seen was a magnaflow cat at 8" length), then an O2 bung, then another cat. At that point, you've effectively recreated the stock setup, but removed the tie-in to the headers. Now you could replace the any/all cats without pulling headers. You might have to extend the O2 sensor wiring but otherwise be able to run all sensors without any trickery.

I know you've got shop access from your build thread, but where I work, I've got access to a full metal shop with fiber laser cutters here at work. Press brakes, welding booths, etc., just not a tube bender that can handle exhaust pipe - I think we just don't have the tooling for it. I think our lasers can go 3/16" stainless on nitrogen cutting and 1/4" on mild steel - oxygen cutting goes WAY thicker but leaves an oxidized film that has to be removed on thicker stuff.. If there's anything I can do, just PM me or reply here.

The GSport by GESI cats are significantly higher quality than the magnalow cats and are 1" (7" overall length) shorter, and are probably better flowing.

Products - G-Sport by GESi - Catalytic Converter Parts and Accessories

They used to be sold by Vibrant, but GESI decided to take over marketing and distribution for themselves.

I have a pair of the 2.5" HO cats to go on my shorties. They look awesome.

What is the Part # for those Cats?

I had seen the old version of those from vibrant but hadn't seen why they were not for sale anymore, and I hadn't been looking for short cats at that time either.. Those are perfect, but dang!, those are like $350 a piece!

I bet you'd do just fine running a single cat on each bank with those. I's still try to run them before the second set of O2 sensors in the hope that you wouldn't need any tricker to remove CELs or codes, but with those being rated for 350-500hp. Even better, they've got O2 bungs available built into the transition fittings, so you could run the sensors that much closer, too.

Are you running any cats after your shorties with those? any sulfur smell?