[mwinemil]

Hey guys. You can see from my post count I'm new to this forum. I have had the opportunity to test fit the new MST Performance Catted Downpipe for Mike@x-ph.com and would like to share my experience.

First, a tiny bit about me. I have been modifying and tuning forced induction cars since the late 90s. I have owned 3 BMWs previously, but this is the first one I have decided to modify. More on the car in a second.
I really don't like anecdotal evidence as it really is based on opinion and I prefer to make my decisions and recommendations based on data. I am a data guy.
But for this job, I don't have a lot of measured facts (no dyno, no draggy, no real way to measure the changes) so this will have to be anecdotal for the most part. I will tell you my experience exactly as it has been.

The car: 2021 BMW M340i CPO. The car is completely stock. I bought it last october. I have had free cars for the last several years, but alas I got a new job and needed to buy a car and this is what I picked. It works.

I received the downpipe from Mike last Thursday. Here's a shot when it arrived:



My initial impression of the DP was that it was huge, but the quality seemed good. The welds are professional, the o2 sockets had nuts in them, the box contained a new gasket, and the DP was in good condition. I had to wait a bit to get access to a lift but I did that today.

I won't go into the individual particulars of installing this because it is already well-documented. The installation was a dream. I was using a lift, and that admittedly makes it a lot easier, but the hardest part of the entire installation was getting the OEM DP out of the car.
The OEM part is a tiny bit longer, I think (I didn't measure it). I took a pic of the two side by side, but the aspect ratio is off making the MST DP look small. It's not, though it is more contoured than the OEM part. It is a little shorter and I think you can see that in this pic:



We had some discussions among the guys that were helping me with the install about waiting to install the o2 sensor closest to the bracket, thinking it would make tightening down the closest nut a bit tough. In the end, we installed both sensors out of the car and fed the DP up through the space.
It fit perfectly and we had it lightly fitted to the turbo, mounting bolts, and exhaust in just a few minutes.

Getting the bottom of the DP into the rest of the stock exhaust was a bit of a pain. There really wasn't much room so it was stubborn. This might be the case with any DP available for the B58 but we had to spread the stock exhaust a bit to get it to fit. But it does fit.

Here are some pics of the DP installed. I'll admit that this is a particularly hard part to photograph once installed but I would say that one thing that is very noticeable is how much room there is with this DP installed.





As for my thoughts? Wow is really all I can say. Even with the stock exhaust from the DP back, it sounds very throaty. It is significantly louder, especially outside of the car.
I did not have a CEL, and took the car through about 50 miles of paces and never got a CEL. I never smelled anything weird either.

I have a stock cold start video and will make a cold start video of this tomorrow and will present them to compare. I also have a few warmed-up revs that I will update this thread with once I get them hosted.
I think throttle response is better, and while I might be obliged to say that it seems like the HP is present, 20 hp (I think the claim is 18-22) is pretty hard to accurately detect with the butt dyno. And as I said before, I don't really buy into that shit so I don't do it.

In the end, this was the first mod I have done to this car and the total install from removing the engine cover to backing off the lift took a total of 1.5 hours. There were 3 points that were irritatingly long in the process:
getting the v-clamp off the turbo, getting the OEM DP out of the car, and fitting the new DP to the stock exhaust. But 1.5 hours isn't so bad IMO.

I really do hope that MST finds a way to deal with their supplier issue with this DP because it is really good. I mean really. You should buy one.

Shout out to Mike@x-ph.com for setting me up with this. Let me know what else you want tested Mike .

Thanks for reading what is bound to be ridiculously long. Cheers guys.


Mark

PS. Sorry the resolution of these photos are so big. I'm too far into this to change them now . Hopefully you can read this ok.

[abbike18]

Originally Posted by mwinemil

Getting the bottom of the DP into the rest of the stock exhaust was a bit of a pain. There really wasn't much room so it was stubborn. This might be the case with any DP available for the B58 but we had to spread the stock exhaust a bit to get it to fit. But it does fit.

I have the AA DP and can say that this part was the hardest for this DP as well (I think regarded as the best fitting and quality DP). Moving the entire exhaust aft to make room, and then slipping over the DP is a challenge. One thing that helped wa susing an exhaust expander on the stock exhaust flange to make the fitment over the DP easier.

Nice review!

[mike@x-ph.com]

Thank you for sharing the review, glad you like it

[mwinemil]

Had to do some driving today for work. Put about another 250 miles on the car. DP is great, nice throaty sound in sport mode (stock exhaust), and is inaudible in the cabin in comfort mode.

Not had a single CEL since it has been installed.

[mike@x-ph.com]

Originally Posted by mwinemil

Had to do some driving today for work. Put about another 250 miles on the car. DP is great, nice throaty sound in sport mode (stock exhaust), and is inaudible in the cabin in comfort mode.

Not had a single CEL since it has been installed.

please post a sound clip when you get a chance.

[bluecarbon]

Any update on those videos? I am on the fence between the AA and the MST

[mike@x-ph.com]

Originally Posted by bluecarbon

Any update on those videos? I am on the fence between the AA and the MST

All info regarding the downpipe are posted on this thread, unfortunately that's all i got.

[AM340iMiami]

Originally Posted by bluecarbon

Any update on those videos? I am on the fence between the AA and the MST

If time is of the essence, just hit mike up and go with the AA DP.

[mwinemil]

Unfortunately the app I got for my phone to measure decibel has no way for me to export the video. I can tell you that it reports that the cold start of the MST DP is about 15 dB higher than stock.

I'll get the revs uploaded sometime today. I did some spirited driving yesterday and I am still quite thrilled with the sound even with the stock exhaust. I'm on the fence about AWE or Dinan exhaust on the car but I can only imagine the combination is going to sound amazing.

Mike had mentioned that MST was having supplier issues but I did read another post on here today that another user listed the MST 6" catted DP as a mod. Perhaps the supplier issue is resolved?

All I can really say is this: I have heard great things about the AA DP but I can't do a direct comparison. I can say this DP is pretty awesome and I'm thrilled it's on the car.

[mike@x-ph.com]

Originally Posted by mwinemil

Mike had mentioned that MST was having supplier issues but I did read another post on here today that another user listed the MST 6" catted DP as a mod. Perhaps the supplier issue is resolved?

The supplier issues have been resolved, please note this downpipe comes directly from MST in Taiwan. It will take a couple of weeks to be delivered.

[MrMegambo]

Please post updates!

[MrMegambo]

a video on the downpipe for supra.

[cyam]

In the photo with OEM and MST, the MST's flex section is tiny compared to OEM. Isn't this a big issue? I see that this flex section is what minimize vibrations and movement of the turbo. I have read a number of DP's have a very tight flex section whereas OEM allows a lot more movement. Problem is we won't see the effect until the turbo is damaged sometime in the future.

Anyone know more about issues with the flex section?

I am looking at a DP but this is a concern for me.

[mike@x-ph.com]

Originally Posted by MrMegambo

a video on the downpipe for supra.

Originally Posted by cyam

In the photo with OEM and MST, the MST's flex section is tiny compared to OEM. Isn't this a big issue? I see that this flex section is what minimize vibrations and movement of the turbo. I have read a number of DP's have a very tight flex section whereas OEM allows a lot more movement. Problem is we won't see the effect until the turbo is damaged sometime in the future.

Anyone know more about issues with the flex section?

I am looking at a DP but this is a concern for me.

It's challenging to provide a definitive answer to your question, as potential damage to the turbo might not be evident until it actually happens. Even with no reported issues so far, one could argue that it's only a matter of time, so it's hard to convince you completely.

If this uncertainty is a significant concern for you, it might be best to consider another brand.

[qballis]

Originally Posted by cyam

In the photo with OEM and MST, the MST's flex section is tiny compared to OEM. Isn't this a big issue? I see that this flex section is what minimize vibrations and movement of the turbo. I have read a number of DP's have a very tight flex section whereas OEM allows a lot more movement. Problem is we won't see the effect until the turbo is damaged sometime in the future.

Anyone know more about issues with the flex section?

I am looking at a DP but this is a concern for me.

Look at Active Autowerke’s GESI catted downpipe. Guaranteed no CEL and has the larger flex section.

I just posted mine in the members classifieds section for a few hundred less than new.

[cyam]

Originally Posted by mike@x-ph.com

It's challenging to provide a definitive answer to your question, as potential damage to the turbo might not be evident until it actually happens. Even with no reported issues so far, one could argue that it's only a matter of time, so it's hard to convince you completely.

If this uncertainty is a significant concern for you, it might be best to consider another brand.

When the two of these were side by side were you able to see/ feel if the flex sections had similar flexibility or was the MST more difficult to move/ flex than OEM? If I had them side by side I could feel if one was more flexible than the other.

Some others have mentioned that a DP they fitted, the flex section was much harder to move than OEM.

[mwinemil]

Originally Posted by cyam

When the two of these were side by side were you able to see/ feel if the flex sections had similar flexibility or was the MST more difficult to move/ flex than OEM? If I had them side by side I could feel if one was more flexible than the other.

Some others have mentioned that a DP they fitted, the flex section was much harder to move than OEM.

The DP that I installed from MST was a prototype and I have since reached out to them to replace it with a production model. I installed this a couple days ago, but having seen this post I did some comparisons.

First, stock vs. MST production, the stock DP is easier to flex. I believe there are two factors that could be attributed to this. The first is the larger flex section (as mentioned before) and the second is age. My stock DP had nearly 40k miles on it when I swapped it for the MST. As was mentioned age will be the determining factor as to how much this moves. I'll add that with the bolts off the block and the vclamp it's hard for me to see how this is a huge deal, unless it's all about vibration. In the end, if this is damaging to the turbo it will be an opportunity to upgrade. I believe not everyone will feel this way .

Here are some pics of the stock DP vs the MST production model:








Once I had the prototype MST DP out I snapped a pic and compared it to the new production model. I didn't have anything substantial to measure the resistance but they seemed relatively similar. If I had to butt dyno the flex, I would say that it's a little easier to move on the production model but it wasn't by much. Pic:



In the end, time will tell how it holds up and how it does in terms of CEL. MST has been pretty good to deal with thus far for me. I think there are quite a few B58 Supras that have this too, so from a long-term standpoint that group would also be worth monitoring.

YMMV.

[checkshipment]

I possess the AA DP and can attest that this aspect proved to be the most challenging during the installation process, which is also considered the ideal choice for a well-fitted and high-quality DP. Rearranging the entire exhaust system towards the back to create space, and subsequently maneuvering the DP into position posed quite a challenge. However, there was a useful technique that facilitated the process—employing an exhaust expander on the stock exhaust flange to enhance the fitment over the DP.

[mike@x-ph.com]

Originally Posted by checkshipment

I possess the AA DP and can attest that this aspect proved to be the most challenging during the installation process, which is also considered the ideal choice for a well-fitted and high-quality DP. Rearranging the entire exhaust system towards the back to create space, and subsequently maneuvering the DP into position posed quite a challenge. However, there was a useful technique that facilitated the process—employing an exhaust expander on the stock exhaust flange to enhance the fitment over the DP.

[DVN.B58]

Damn man. MST or AA??

[mike@x-ph.com]

Originally Posted by DVN.B58

Damn man. MST or AA??

AA is more proven to be honest

we got our first MST CEL last week

[DVN.B58]

Originally Posted by mike@x-ph.com

AA is more proven to be honest

we got our first MST CEL last week

Is there a significant difference between the two? Performance wise/sound/capability wise?

I just emailed you guys on your website about it too lol.