GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

How many people run an aftermarket downpipe in CA?

Faceman

Drag Racing Champion
Location
Long Island
Car(s)
'17 GSW 4Mo
I have a IS38 on a 1.8 GSW with AWE downpipe and all my readiness monitors are (y)
 

StorableComa

Autocross Champion
Location
Long Beach, USA
Car(s)
17 GSW S
I have a IS38 on a 1.8 GSW with AWE downpipe and all my readiness monitors are (y)
Didn't know APR had readiness with a DP in IS38. Last I heard from them was you have to swap to a stock DP due to their tunes ignoring the CEL from the O2 monitor. Are you using their Non-straight/test pipe DP file? Be curious as to what your VCDS readiness numbers are.

They claim stage 1 is the only emissions CARB tune they have, and I've only heard of IS20 with GTI stock DP having no readiness/CEL tampering on APR. Though emailing them is slow, and their website only show the IS20 with stock DP dyno, not 38 with a stock DP.
 
Last edited:

Father Seth

Go Kart Newbie
Location
SoCal
Car(s)
2015 Golf TSI
Biggest issue would be the ODB2 hook up and readiness with the tune. They don't do sniffer smog anymore on newer cars in CA, it's a visual inspection and a readiness check. Currently I think APR has one on the 1.8T for an IS20 swap using the GTI DP, but I don't believe I've read of any IS32 stock DP tunes that will pass readiness on the GTI or 1.8T

Turbo if a OEM version might be okay, DP is questionable as I believe they look for CARB numbers on the DP. Not completely sure on that, with the heatshield in the way and a lazy tech you could get away.
Swapping the DP to stock would not be an issue, the turbo swap is more of a hassle though. If everything was stock except for the turbo (IS12 to IS20) that's what I'm curious about. For CA people I'm not sure I can get an answer from someone with experience because 2015 cars don't need smog till 2021, so any speculation in the meantime? Just genuinely curious because like someone else said, the turbos look nearly identical, and if I have a stock tune I wouldn't expect the emissions to be worse because it's still should be pushing light boost?
 

StorableComa

Autocross Champion
Location
Long Beach, USA
Car(s)
17 GSW S
Swapping the DP to stock would not be an issue, the turbo swap is more of a hassle though. If everything was stock except for the turbo (IS12 to IS20) that's what I'm curious about. For CA people I'm not sure I can get an answer from someone with experience because 2015 cars don't need smog till 2021, so any speculation in the meantime? Just genuinely curious because like someone else said, the turbos look nearly identical, and if I have a stock tune I wouldn't expect the emissions to be worse because it's still should be pushing light boost?
APR so far is the only tuner i've read with an OTS turbo swap tune with stock DP that retains readiness. They have an IS20 with stock GTI DP file that retains readiness like a Stage 1 file would - I believe, could be wrong. All others, at least for the 1.8T, seem to be with a aftermarket DP on their turbo swap. This normally disables the O2 sensor CEL you'd get for the modified/missing Cats and higher flow.

I would assume at this point that's the only way to turbo swap in CA with smog as the GTI DP is CARB certified. So the question is just what the readiness numbers read with the tune, which should be fine as the stock DP file doesn't modify the O2 sensors I believe.
 

GTI_Jerm

Go Kart Champion
Location
SoCal
Swapping the DP to stock would not be an issue, the turbo swap is more of a hassle though. If everything was stock except for the turbo (IS12 to IS20) that's what I'm curious about. For CA people I'm not sure I can get an answer from someone with experience because 2015 cars don't need smog till 2021, so any speculation in the meantime? Just genuinely curious because like someone else said, the turbos look nearly identical, and if I have a stock tune I wouldn't expect the emissions to be worse because it's still should be pushing light boost?

It would actually be 2023 for a 2015 car as we now have 8 years for smog. It’s really the only reason I went stage 2, as I plan on moving up the VAG chain 🤷🏻‍♂️

I’m also curious with guys doing turbo swaps and emissions testing for CA too tho. Still gonna be some time until we find out. I’ve been eye an is38 upgrade for a few months now.
 

J Peterman

Go Kart Newbie
Location
USA
Are smog shops really looking at stamped part codes on cats in CA? I doubt it. I would think if you have a tune that maintains readiness, a downpipe that doesn’t scream it’s aftermarket with obvious logos, and a cat that doesn’t throw a CEL (spacer or not), you pass.

What I’m really interested to find out is what people with MPI setups are doing to pass in CA. Do you just flash back to a stock file? Any issues passing or do you actually need to remove fueling hardware?
 

StorableComa

Autocross Champion
Location
Long Beach, USA
Car(s)
17 GSW S
Are smog shops really looking at stamped part codes on cats in CA? I doubt it. I would think if you have a tune that maintains readiness, a downpipe that doesn’t scream it’s aftermarket with obvious logos, and a cat that doesn’t throw a CEL (spacer or not), you pass.

What I’m really interested to find out is what people with MPI setups are doing to pass in CA. Do you just flash back to a stock file? Any issues passing or do you actually need to remove fueling hardware?
Depends on the shop and the car I suppose. You could have a 700HP Kia, and they might not even pop the hood if it looks mainly stock on the outside because it's a Kia. GTI and an R, they might, though cops will make you pop the hood if they're feeling like it with those cars and you get popped for loud exhaust.

Some shops have pits and cameras that look at the underside of the car and record the tech, these ones tend to look a little closer. Though there are always those shops that look the other way, FB groups around here ask about them a lot.

I'm hoping with the wagon they don't really look, but it's hard to tell. It's only visual and a ODBII readiness check in CA, so they might look for CARB numbers. The tune that retains readiness, at least with the 1.8T would be the issue I think. Like I said, in my looking around earlier in the year APR is the only one that advertises a stock DP turbo swap file - others might, but I haven't read about it yet so i'm not sure if Uni or UM do.
 

Jovian

Drag Racing Champion
Location
Sunnyvale, CA
Car(s)
2016 VW GTI
CA resident, I have stuck with the stock downpipe on my GTI. Honestly I have been fine with Stg1 and have both 91oct and E30 profiles. The E30 profile is more than enough for this FWD car. I probably would be looking at an R for the AWD if I wanted to have more HP than I do currently. Most of my drives are in the mountains where the corners keeps my speed in check. Not really going over 80mph often and I like the low end torque of the IS20 so bigger turbos are not as desirable to me.

I purchased mine new in 2016 so I still have time before I have to take it in to get inspected. Still though I dont want to deal with flipping parts back and forth then. I plan on keeping my car until it financially doesn't make sense. For me that is a years worth of repairs exceeding a years worth of new car loan payments. I expect to get about 8-10 years out of the car like I did my MK5 before this.
 

GTI_Jerm

Go Kart Champion
Location
SoCal
CA resident, I have stuck with the stock downpipe on my GTI. Honestly I have been fine with Stg1 and have both 91oct and E30 profiles. The E30 profile is more than enough for this FWD car. I probably would be looking at an R for the AWD if I wanted to have more HP than I do currently. Most of my drives are in the mountains where the corners keeps my speed in check. Not really going over 80mph often and I like the low end torque of the IS20 so bigger turbos are not as desirable to me.

I purchased mine new in 2016 so I still have time before I have to take it in to get inspected. Still though I dont want to deal with flipping parts back and forth then. I plan on keeping my car until it financially doesn't make sense. For me that is a years worth of repairs exceeding a years worth of new car loan payments. I expect to get about 8-10 years out of the car like I did my MK5 before this.

What ethanol sensor are you running? I’m back and forth on whether to move to a Cobb AP or just jump to an is38 and stick with APR.
 

Jovian

Drag Racing Champion
Location
Sunnyvale, CA
Car(s)
2016 VW GTI
What ethanol sensor are you running? I’m back and forth on whether to move to a Cobb AP or just jump to an is38 and stick with APR.

Currently I’m not running an ethanol sensor. I’m doing the math each fill up and testing the pumps ethenol content each time. Thankfully the pumps around me are very consistent around E80 reguardless if it’s Pearson or Propell as the fuel provider.

I’m very happy with Cobb and EQT, you won’t regret making the switch.
 

GTI_Jerm

Go Kart Champion
Location
SoCal
Currently I’m not running an ethanol sensor. I’m doing the math each fill up and testing the pumps ethenol content each time. Thankfully the pumps around me are very consistent around E80 reguardless if it’s Pearson or Propell as the fuel provider.

I’m very happy with Cobb and EQT, you won’t regret making the switch.


Test kits adding up ? I fill up 1-2 times a week so that would become very tedious after awhile 😅
 

Raguvian

Drag Racing Champion
Location
Denver
Car(s)
2019 GSW 4MO 6MT
If I go with an IS38 on my wagon and use something like a stock R downpipe, would I be able to just flash to a stock tune and drive very gently to the smog station and then swap back? The downpipe will look stock and the turbo doesn't look very different from where it's positioned in the engine bay.

I guess the main issue would be driving the ~50-100 miles to get the stock tune's readiness sensors cleared with the IS38. Probably would run like crap.
 

Jovian

Drag Racing Champion
Location
Sunnyvale, CA
Car(s)
2016 VW GTI
If I go with an IS38 on my wagon and use something like a stock R downpipe, would I be able to just flash to a stock tune and drive very gently to the smog station and then swap back? The downpipe will look stock and the turbo doesn't look very different from where it's positioned in the engine bay.

I guess the main issue would be driving the ~50-100 miles to get the stock tune's readiness sensors cleared with the IS38. Probably would run like crap.

I don’t know if anyone who has done this but your logic is sound and I think you will pass.
 
Top