Catted Vs Catless Downpipes + The Issues With Boost Creep 

Me who has n/a subaru: "Yes, boost creep, problem noted 👁👄👁"

I feel it’s important to point out that while a catalytic converter does reduce CO emissions, the main purpose of the design is actually to reduce smog emissions. Smog is a catch-all term for oxides of nitrogen (NOₓ) which are a medley of molecules formed during combustion which consist of a nitrogen atom bonded with various numbers of oxygen atoms, hence the ‘x’ in the name. The key to the cat’s function lies in bond energies of molecules, and the triple covalent bond in NOₓ molecules have much a much higher bond energy than the double bonds in CO, CO₂ O₂, N₂, and other common exhaust products. To remove the NOₓ molecules, the cat media reacts with the exhaust gas by becoming extremely hot, reaching temperatures comparable to the combustion chamber where the NOₓ was formed. Since it takes the same amount of energy to break the bonds as it does to form them, the NOₓ molecules disassociate into monoatomic nitrogen and oxygen as they pass through, and when they exit the cat the temperature drops below what would be required for NOₓ molecules to re-form. The result is a significant decrease in smog emissions and the presence of smog is the smell the emits from a cat-less setup.

This channel is quickly becoming my favorite. Love the channel man I've learned so much new wrx owner here. Its my first Subaru so i wanna do it right. Thanks for the great content!

bought my 2012 in December and your videos have shown me that the original owner and his tuner did my car right. Thanks for all the great Subaru info

Bro I love this channel so much. The way everything is explained is super clear and informative. I seriously hope your success comes because it is beyond deserved.

I dont have a cat I have a dog, does that make me...catless

scrolling through sti vids for my sti and i see the TMG banner in the back. Much love brother!

Its also important to note what hardware comes in the box with certain downpipes. Sometimes a cheaper downpipe will be missing a gasket or resuse bolts that were already on the car instead of new hardware.

All of your older videos are very entertaining brother. Have a great week.

We have a subaru WRX. This was very informative. We appreciate the breakdown. This cleared up alot of questions we had.

Yessss - I really wanted this topic. Thanks for doing this ❤️

The intro alone got me😂!! Very informative altogether 🙌🏽😎

Love this guys’ videos keep it up man !!!

Love this video, I’m new to the subi community and I’ve learned so much, thank you!

Been looking for info on this topic everywhere. Dropped a sub. Keep it up!

Best wrx channel out there ,, been watch and subscribed at 771 and Anything I need to know I watch your videos keep it going

I don’t own a Subaru but still enjoy watching your channel. Good info and nice car

Appreciate your channel. As a 2005 Subaru Legacy GT owner, its helped me understand ALOT. Kudos

Always killing it with the great content. Stay safe out there in Wa...craziness. Ouuuu T-shirt on its way. Will be rocking it out here at the east coast Subi meets when they finally happen

Perfect video. Thanks! Just boosted my miata and noticed I was running lean at higher RPM's. I also noticed the boost was increasing from where I had it set. I installed a test pipe while installing the turbo system... but I'm thinking the cat is going back on. Thanks for explaining everything!

Bro you are my new favorite channel.

Loving the videos man! I have owned a 2015 sti for 3 months now, went from a 99 GC8 NA to this and am so happy with it, your videos are very helpful for me and your great at explaining I can tell you know best!. Respect from Perth Western Australia 🇦🇺

Keep up the good work, Love the videos. Wanted to see if you are considering installing aftermarket seats for the WRX/STI or the BRZ and of course making a video?

"make sure you wash your hands and not touching people butts?" Love the content my dude!

Video on when to consider getting a tune , pro tune / E tune etc. love the channel, I’m in the army right now I ETS in 2 months yuhhhhh

Great video. Can't wait for the ewg video need one for my car as I have a grimmspeed limited catted downpipe but still having boost creep issues on my car

Another great video! Keep it up!

Your vids makes me more excited about finally buying a wrx 😁

This is one of my favorite channels 👍🏽👍🏽👍🏽👍🏽👍🏽👍🏽👍🏽👍🏽👍🏽

I've ran an Invidia catless j-pipe and a resonator delete on my 17' WRX for over year now because I really wanted that "diesel" spool sound. I've never had any boost creep oddly enough and have always been aware of the cons of running the set up. Then again this car has been through absolute hell and it's a miracle it's even running still lmao

I just got the Invidia catless downpipe and it's amazing. More flames, pops and noise. I had a Grimmspeed look-alike and I ran into a fitment issue because the internal wastegate was hitting a flange on the downpipe. EWG coming in the future...

i subscribed right when you gave the be safe warning hahaha love the energy

Great video and great explanation and comparison. I was very on the fence of what to go with and i have heard catted is the way to go but i wanted them “racecar vibes” but now i think i will go catted thanks alot!

Catted downpipe to keep it friendly with our neighbors😂

Great video and great explanation! Thanks very much!

Great video again appreciate the info🤙

I have always liked your videos good content!

thoroughly well explained thanks!

Ewg with catless downpipe is a must. My wrx running strong with 178,xxx, learned a lot from your videos. Keep up the good work fellow Washingtonian.

i need ur motivation lmao good stuff as always

I’m very glad I subbed to you, you definitely know what you’re talking about through all of your videos. I was told by my local tuning shop to get a catted J-pipe, is that a down pipe still? Is it basically just another way of saying downpipe?

Great informational video. New subscriber. Going catted downpipe for my N55, will pair it with my charge pipe and BM3....hip hip hooray!

My new subie guru! 🙌 Love the info.

I smell my cats all the time. They're house cats, eating the same food, pooping in the same litter, and they smell completely different. It intrigues me. Nonsense aside, I learn something new in every one of your videos. You're becoming my favorite channel. I mean, I paused binging Breaking Bad to watch this. You're doing something right!

I didn’t know OTS maps don’t support catless downpipes, you saved my ass as I was JUST shopping for one👌🏻

Yes yes please please do make a video on properly wrapping an exhaust 🙏

Hey man love the video. Also what kind of wheels are you rocking. Very dope. Thanks for your time.

Great video really informative

Just discover this channel and really like it! Which video does he talk about pros/cons of voiding a warranty? Asking for a friend 😝

Really like your channel man, really chill vibes. Ill be sure not to grab anyones butts lol.

Thanks for the info..new subscriber here..I appreciate all the info.cheers.

I've had my WRX for a while now so I know most of the information. But it's always good for a refresher and new owners. Good job we appreciate the effort

We need more pics of this wrb sti, looks awesome

Sheeit dude i didnt know youre studying microbiology! My grandfather is a hugeee microbiologist here in the east coast. He a big part of laboratory alliance hes written books and all. Love your videos man

What's up bro its ya boy @sonic_sti5335 I just wanted to say big big thanks for all your videos, u give detailed info on everything u base ur topic on. I always look forward to what u got next, preciate all u do brotha😉🤙🏼

Ouuuuuu! Great vids man!!!

2012 wrx tuned on 19psi.... intake top mount turbo back exhaust

I was looking at the turboxs catted j pipe since it’s on sale for a good price.

Outstanding.

Hey man, I love your stuff and the information you provide. I am looking at getting into a 2015+ wrx. I plan to go stage 2. I am curious what your thoughts of buying a rebuilt title wrx. I plan to do mechanic check and everything that goes with that. Wanted to know your opinion on it though. Thanks!

Great video

This guy don’t miss

I know the car has changed since this video. But that thumbnail looks soooooo goooood! I wonder if a gt wing would suit my wrx. I track my car and would love to add some downforce.

This was the best advice I've heard and I almost got catless downpis lol.cheers mate

Good info! I may add - If you want to run an OEM VFxx turbo on a catless downpipe, I recommend porting the internal wastegate (which is what I did on my car) It’s a simple process. Remove your turbo, take off the wastegate actuator, and remove the V-band clamp that attaches the exhaust housing. Use a mallet and remove the exhaust housing, being careful not to damage the turbine wheel. Take a Dremel and a grinding bit, and round off the corner that leads exhaust gas to the wastegate. DO NOT ENLARGE THE WASTEGATE HOLE, you’re simply smoothening the hard edge that leads to the wastegate. This encourages exhaust flow out the wastegate instead of going through the turbine. There are a few videos and forum posts on this process, so do your research. I’m on a VF48 e85 at 20 psi, never had an issue with creep. A 3-port EBCS might help, but there’s nothing that can truly eliminate creep other than having a larger wastegate Last and most important, GET A REAL TUNE 🤣

BOOST CREEP FIX!!! I used to own a 2003 WRX and then a 2004 STi. There is a fix we used to do on those for boost creep on a STOCK TURBO. We would enlarge toe orifice on the wastegate. I did several of them for other people too. When you have the downpipe off of the turbo you remove the clip and rod from the wastegate valve. Open the valve and grind a VERY SMALL amount off the wastegate hole and keep it round. You can always take off more, you can never put it back. if you take too much material off you won't get enough boost. Solved the creep issue on my STi with a catless downpipe and many others too.

I’m planning to get a Tomei Expreme Ti single exit cat back for my 2020 wrx.

When he was walking towards the camera at the beginning, I was killing my self laughing! Hahaha

Love the videos man. Where can I get a protune or etune here in WA?

What I learned.. always wrap your downpipe!! Got it

It’s nice to find a channel based in Washington

I have a catted jpipe currently but I’m looking at going catless in the future just to have fun with pops and flames every once in a while but I’m not looking forward to having to install again

Might be stupid question. But if I go catless... And get headers with external waisgates, will that work as the waistgates for boost creep?

unrelated question, but what wheels are those? (awesome video by the way man!)

I went Catless on my 2018 WRX. To minimize boost creep, I put on the Killer B EWGs and this thing is loud AF now.

Replacing my current dp with the grimmspeed pipe. Ive got a lot of their parts installed on my 05 lgt, and the quality is hard to beat.

smeedia huge fan!! currently collecting mods for my build watching your vids, have a blouch 2.5xtr 10cm with invidia catless down pipe would porting the iwg housing be sufficient enough to eliminate boost creep? or should i juat run a ewg? what causes boost creep when running a cattless downpipe?

How is the microbiology career like ? It sounds super interesting. Subie lookin real nice btw

I know this comment is late but this is why I like my safety only county.... no emission. I'm catching up on all the old videos

Nice work brother , I have a Sym's catted downpipe , I have run without it (cattless) and don't see much difference . I'm all in cause $3k I have to like it !

Bro, 100% video 👌👌. I bought a bottom range 09 wrx hatch. Nothing done to it. All I've done is 3" turbo back decat. STI style rear muffler been cut open and all the crap removed. Welder back up. Took housing off oem air filter front part to reviel filter. Half inch spacer last joint before rear muffler. Got the rumble, got the turbo spool sound, got natural pop and bang through gear change. No boost problem, and it's like a totally different car. It almost pulls my hands off the steering wheel through gear change. I'm in the UK running standard UK 99ron petrol???

I keep getting boost creep on a stock 2021 sti Catback exhaust running the Stage 1 91 octane ACN tune

I have an Invidia Q300 and the stock downpipe on my 2009 Impreza WRX currently. I’m a little nervous about emissions (I want to go Catted) and also sound laws in Massachusetts are WAY more strict

Love my invidia catless jpipe and q300 exhaust. Downside is gassing yourself out at red lights or telling a passenger what that smell is

I would love to put one in my 21 Type s preferably catted

I need some advice ! I have a 17 wrx and currently catless and experience boost creep and I read you need dual ewg which is out of budget . would I lose hp switching to a catted down pipe ?

by heat wrapped is that the foil type material? I bought mine with the fabric-like material. but is not the full pipe is only closer to the turbo

Can you do a things to know before you straight pipe I want to straight pipe my wrx but all these exhaust terms and stuff got me so confused so fat I only have a remark muffler delete

A great video, thanks. I am installing a catless downpipe there. Should I drive below 5,000 rpm at all times before I get a pro tune?

Yo Yo! Great vid as always! Recently pro-tuned my 06 WRX to stage2+ w/DC intake and STI intercooler BUT without adding a new catback exhaust for emission/noise reasons (I live in VA). Will putting an HKS Hi-power on a stock 06 downpipe work fine or should I do the catted downpipe as well? I'm hoping it'll fix the DAM problems I've had since we got it tuned. It wants to run faster but restricted by the exhaust airflow. Thanks in advance!

Havin bad boost creep right now being in Buffalo at around 30 degrees. Hopefully it gets better in a couple months

When talking about an EWG, would a blow off valve work in this case to mitigate boost creep?

Curious what TPMS sensors your running on your wheels? Every website say stock TPMS sensors won’t fit properly.

Regarding ceramic coating the down/j pipes: I'm assuming there's some specialized coatings for that specific purpose? Or does the plain old ceramic/graphene coating usually for the paint work the same? ✌

Tanner. I want to go invidia catless jpipe but I was told an EBCS would be plenty to prevent boost creep. Do I need EWG too?

Would it be ok if I put a catless Down pipe on my car and kept the rpm’s low to drive it to get tuned

Will I have boost creep on a fully stock but decatted 2008 S-GT Hatch? The first cat is original but emptied the second cat is straight pipe with o2 sensor and spacer. (Its a ej20X japanese wrx)

Great video buddy. My STI has sports cat and was tuned at 1.25 bar three week later it’s at 1.33bar and has stayed there since. 12 months later it’s still at 1.33bar. I’m guessing it’s boost creep, but why hasn’t it gone higher? Should I be worried? Cheers

I thought I heard something about catless downpipes and oil consumption(blue smoke) I'm not sure how these are related unless there's always oil consumption but just easier to see on catless FA20s. Any insight? And oil pressure regulators needed?

Found a used Invidia divorced down pipe and a turbo XS non divorced down pipe both have high flow catts, just wondering which would be better and if I need to run a wastegate with the divorced or not