Has anyone made their own cheap catted DP by buying catless and adding cheap cat?

[danbfree]

Edit: So we can consider this question solved, I've decided to stick to a full catted DP, either hoping the ARM I ordered on an awesome deal off eBay actually gets shipped, but if it doesn't then with the refund I'm going with an ARM that I found a good deal on, but hopefully this can help someone in the future see what a pain it would be to follow thru on this idea.

48 state legal cats are only like $55, so is it possible to buy a cheap catless DP like THIS and have the cheap cat welded in above the O2 bung and be 48 state legal with a decent improvement in airflow?

Theory would be to fit an 11" total length cat between the V-band and 02 bung on a 2 piece DP like this. I'm sure the ends of the cat cut be cut down further to maybe 8" total length to help fit it? Or, as it says in the description, would have to add to the rear section, like on a CTS catted DP - with o2 spacer used on higher mounted bung and the cat below? I suppose that would be a cheap way to create your own CTS style catted DP, but they smell on startup until the cat further below heats up. If you can fit a 400 cell EPA cat above the O2 sensor, you wouldn't even need a spacer to pass smog/no CEL without any special tuning - I'm running a JB4 and plan to keep it that way for now. Of course, many people just run catless, but I imagine it would still be a massive improvement over the very restrictive 600 cell stock DP with sharp bends.

EDIT: Now considering THIS one that is not as cheap with a larger v band section and indeed just do it like a CTS catted and rely 100% on a the big fat L shape O2 spacer and cat after that. It will smell until it warms up, which will take longer since it's not as close to the turbo/engine to heat up faster.

 

[jimlloyd40]

Not sure if anyone else has even considered this before, but Id like to know what the in/out diameter of the stock cat converter is so I can cut the stock one out (600 cell 50 state legal) and replace it with a 400 cell 48 state legal one. I know our exhaust is 2.36"/60mm but does anyone know the in/out diameter of the stock cat itself? I'm thinking for $55 for the EPA 48 state legal cat (only CA and NY illegal) and some cutting/welding, that would be some actual legal airflow improvement with no CEL. I'm pretty sure for simplicity purposes they are all sold new with 50 state legal cat. I know almost everyone goes with a whole DP usually, but thought this might be a budget legal way to improve flow for those of us not in one of those 2 states.

You can buy just the cat for $55?

 

[danbfree]

You can buy just the cat for $55?

Yup, eBay HERE... there are ones even a few bucks less, but the $55 one even has a full 5 year 50k warranty.

 

[danbfree]

You can buy just the cat for $55?

I also changed my mind about using the stock DP at all and thinking may as well use a cheap aftermarket catless and add this cat for a ~$200 total price 48 state legal 3" catted DP instead of paying $450+ for an aftermarket DP with cat already installed... now just have to find those cheap $150 catless DP's again, some sites are cracking down on selling catless now.

 

[jimlloyd40]

I'll be curious about the quality of the cat when you get it.

 

[danbfree]

I'll be curious about the quality of the cat when you get it.

I mean, it is what it is, 48 state legal ceramic Chinese made one... Of course, they have similar in name brand G-Sport/Gesi for ~$135, was just brain-storming ways to do a budget build and add some smog legal airflow in one. If you can get a Majesty intercooler that truly reduces IAT's better than 80% of name brand IC's for 40% the price, I don't see why we couldn't build a DP that works just as well too... I mean, I would never put an off-brand turbo itself on my car, especially when used excellent condition OEM one's can be had cheap, I got an IS20 I still need to install for $240 with only 20k miles on it, but there are certain non-critical/non-moving parts we can go cheap on if we want to, hehe.

 

[S-4Motion]

Only slightly related, but couldn't you cut out the stock cat and mate it to a 2.5in/3in mandrel bend and make your own downpipe like that, or is the Cat itself the choke point on the stock downpipes?

 

[danbfree]

Only slightly related, but couldn't you cut out the stock cat and mate it to a 2.5in/3in mandrel bend and make your own downpipe like that, or is the Cat itself the choke point on the stock downpipes?

Good point, I actually originally asked my question that way, but when you see how sharp the bend is right where the cat is, then you see why it would be tough and prob not much gains... so I found the actually decent looking DP for $136 at Walmart with free shipping (that like $200 with shipping on Ali) so I changed the question itself... BTW, $2000 for this OEM part, holy shit... But yeah, with 2 cats to deal with and weird sharp bend you are better off going catless DP to start.

 

[El_bigote_AJ]

I did this with the first DP I ran on the car, even modded the fitment if the eBay pipe sucks. Also… no way putting it where you marked up would fit it would push the bend to far down/over … you would have to fit a cat where the flex is.

*I don’t run it anymore either…moved up to a trackslag

https://www.instagram.com/el_bigote_rabbit/p/CVy0Sokp2He/?utm_medium=share_sheet

 

[danbfree]

I did this with the first DP I ran on the car, even modded the fitment if the eBay pipe sucks. Also… no way putting it where you marked up would fit it would push the bend to far down/over … you would have to fit a cat where the flex is.

*I don’t run it anymore either…moved up to a trackslag

https://www.instagram.com/el_bigote_rabbit/p/CVy0Sokp2He/?utm_medium=share_sheet

OK, so would have to be full on CTS catted DP style with cat down below on the straight section... this is what I figured.. and there are a few different styles of cheap Chinese DP's, was your poor fitment one like this with just a small V band section? There are others with a bigger v band section that could be used the same way I'm thinking and maybe fitment is better... Edit: NM, saw your pic and you def had the exact same one with small V band, I just wish the bigger V band ones could be found cheaper, they are like $250+ with shipping off Ali, damn,

 

[danbfree]

I'm thinking THIS one from Depo Racing would be worth $250 with far better fitment, worth it for the quality... Even with $55 cat added it would still be well under the $450+ catted DP that's not smog legal. I already have the APR 76mm to 60mm adapter coming to fit the 1.8L 2.36"/60mm exhaust.

 

[GTI Jake]

Chinese cat is an absolute lie. It’s legal for cars built prior to 1974, not your mk7. You can get a tuna sandwich for a dollar, but it’s not tuna lol.

Depot is absolute dog shit quality & fitment, a buddy at work has one and not only does it not fit, but it also broke in the first year of use.

You 100% get what you pay for & I’d absolutely recommend you back away from the eBay and keep your superior OEM downpipe. 1.8T, even with is20 doesn’t benefit much from a downpipe anyway.

 

[danbfree]

Chinese cat is an absolute lie. It’s legal for cars built prior to 1974, not your mk7. You can get a tuna sandwich for a dollar, but it’s not tuna lol.

Depot is absolute dog shit quality & fitment, a buddy at work has one and not only does it not fit, but it also broke in the first year of use.

You 100% get what you pay for & I’d absolutely recommend you back away from the eBay and keep your superior OEM downpipe. 1.8T, even with is20 doesn’t benefit much from a downpipe anyway.

Well, removing any functioning cat is illegal to begin with, I think most people running catless don't give a damn. At least I want to run halfway clean, I'd just like to improve flow, move heat away from the engine bay, and not smoke/gas myself and others out while keeping overall emissions down. I have seen some legit gains in the JB4 thread with DP's catted or otherwise, so I dunno... As far as "you get what you pay for", well, that went out the window a while ago with Chinese labor, some items like a Magic/Majesty IC absolutely kick ass for the money, you just have to deal with a bit of fitment issues... As far as DP, I actually already purchased a MAP catted for 25% off from a one-off eBay listing and it has the G-sport 300 cell that is not compliant, but at least seems more legit than a $55 cat but, I ordered a week ago and it hasn't shipped so I'm already thinking it's some kind of scam as it's supposedly brand new from what I see *afterward* has bad ratings as a seller (they show his *buyer* rating upfront) so I'm just preparing to cancel my order and come up with plan B. Maybe I'll just gut the 2nd cat and do a res delete and call it good.

 

[Acadia18]

One thing to keep in mind, and this is pretty state specific, but just because a cat is "epa approved" doesn't mean it won't cause a cat inefficiency cel and fail a state inspection.

 

[danbfree]

One thing to keep in mind, and this is pretty state specific, but just because a cat is "epa approved" doesn't mean it won't cause a cat inefficiency cel and fail a state inspection.

Yeah, we have CA emissions on new cars up here in OR but 48 state with just OBD check and no visual for smog and I already have a spacer ready to go as well. Just using a JB4, I have to make sure all readiness stays good. If the MAP I ordered does end up getting shipped and I get it, at least it does have the 300 cell cat before the O2 sensor, so along with a spacer I should totally be fine.