08-11-2015, 05:03 PM | #1 |
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HJS 90 81 2010 EU6 N55 F2x/F3x Catted Downpipe
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To complete AnooooOH review of LightWeight Exhaust + HJS catted DP, here is my review of newly introduced HJS EU6 catted downpipe. My M235i is my daily car. Basically, I mainly focused on the reliability and on improving throttle response before carrying out any ECU tuning. Aim would not be to have the better power or torque absolute values but the best power delivery (from idle up to 7000RPM with no max HP at 5000RPM and nothing after) with less turbo lag as possible and reliability not altered over stock. All mods should work without triggering any CEL, nor soft error, nor not correct car behaviour. Mods so far:
Last mods:
As I said, I'm quite sensitive to throttle response. There is a very small lag from factory, a little increased with ATM FMIC. So aim of DV+ would be to reduce On-Off-On throttle issue and sport cat to have turbo spool faster and cooler. I've measured my factory catalyst at 975°C so I'm not quite confident with its reliability on the long term... So why HJS? Because they are the best catalyst core manufacturer. I'm quite confident with them since they are makers of brands such as Alpina and some BMW sport cats. So I've been waiting HJS downpipe since mid January when I was aware that HJS was working on an ECE homologated catted downpipe for M235i. I contacted HJS and product was forecast for March and then June. I ask to HJS the following:
And mid June, product was announced HJS website and HJS listed N55 F2x/F3x EWG supported cars. And then available to sale mid July. I ordered HJS 90 81 2010 EU6 catted downpipe to Marc @ Lightweight Performance. Very nice and professional guy, quick shipment. I ordered to my local BMW dealership clamps and gaskets in order not to have any leak:
Some photos of HJS downpipe: Installation was straightforward. Most difficult part was to put in place exhaust V-Clamp correctly (its gasket part...). There is no need to remove exhaust. Only need to release it at its next mount point after downpipe. So far, I'm very happy with this downpipe. It's as quieter as OEM one in comfort mode while cruising. So perfect for a daily driver car. It adds a very nice note when throttling. It's less raspy, more clear/vocal. Throttle response is clearly improved and what annoyed me has disappeared. It's even better with GFB DV+ installed. Perfect combo. On/Off/On are now stellar. There is no soft error/CEL or anything. Last edited by quenotte; 09-07-2015 at 03:05 AM.. |
08-12-2015, 01:53 PM | #3 |
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m235i and HJS downpipes
I have already purchased HJS downpipe. Actually it has 300 Cell cats (information confirmed by Lightweight). As i suspected the downpipe, it has two cats installed after each other in the downpipe. One is after second lambda sensor. Maybe an additional few HP/NM if you remove the second cat.
Fitment was perfect, installation was straight forward. I also have ER charge pipes (turbo to intercooler, intercooler to intake manifold), but not yet installed. Also purchased Challange SS brake lines, but not yet installed. Will go with Motul RBF660 brake fluid. I also has Awron display and some BMW Performance goodies. Other power up modification is under consideration. As for the HJS downpipe, it has a little bit more smell than OEM downpipe in some circumstances, but its ok for me. |
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08-12-2015, 02:07 PM | #4 |
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Drives: 2019 G30 M550i
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How are you measuring the catalyst temp? The car does not have an actual temperature sensor. Any temperature reading you are getting is a approximation. Also, I would not be quick to discount the OE design based on the temperatures you are seeing. Many hundreds of hours going into designing stuff like this. You not liking the temperature does not mean it is not within operating parameters.
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08-12-2015, 05:52 PM | #5 | |
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I didn't think that stock design is a flaw. I just prefer to have less constrainst on turbo, lower temperature. But the key element is clearly the better throttle response. |
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08-12-2015, 06:01 PM | #6 | |
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I will try to post some video. To my mind, it's the same device as on their website! Price was 1150€ Net, same price as Fabspeed downpipe delivered here and ECE homologated so no problem with emissions. Car is still Euro6 compliant. |
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08-12-2015, 06:07 PM | #7 | |
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I've ask HJS to confirm if this is a 200-cell cat or 300-cell one. I also had some sporadic smells with stock downpipe, as with HJS one. To my mind, nearly the same. |
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08-13-2015, 02:33 PM | #9 | |
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I am very happy with HJS downpipe. I already ordered GFB DV+ to my car. |
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08-13-2015, 03:47 PM | #10 |
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Great review!!
The first hjs 200cell have exactly the same power output as the newer 300cell cats.
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08-21-2015, 09:41 PM | #11 |
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Great write up quenotte!
Have a question to those who have installed the DP. Is it necessary to purchase new clamps and gasket for install? Have any of you installed the DP with the original stock clamps/ gaskets? Any problems? Thanks! |
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08-22-2015, 04:06 AM | #12 | |
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No Problems!
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08-22-2015, 09:45 AM | #13 | |
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Turbo clamp because BMW indicates to change it each time (low tightening torque and exposed to lots of heat). Exhaust clamp because gasket is integrated in the clamp so that it's very difficult not to damage it when removing it from stock downpipe. In the first post, I've mentioned all clamps and gaskets parts that must be changed to have a trouble free install. I'll will emphasis that more. It's a 50€/USD ticket compared to 1150€/USD downpipe cost... |
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08-22-2015, 11:06 PM | #14 | |
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09-05-2015, 11:34 PM | #15 |
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Hello everyone,
I own a M235i 2015 and it's equip with the Dinan Stage II, Dinan Cold Air Intake, Dinan highflow exhaust, Go Fast Bits Diverter Valve + and just had the Fabspeed HighFlow Downpipe. My question is, two days after I got the downpipe install at my BMW dealer, the check engine light turn on ! I was under the impression that these kind of Downpipe were design to not turn any lights on ! Is it the downpipe or the DV+ that turn it on ? Because I got them install at the same time. I was also thinking that the Fabspeed DP and the HJS DP were the same !? Thanks Thanks. |
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09-07-2015, 03:02 AM | #16 |
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HJS is manufacturing cats for various applications/customers.
Then, those customers like Fabspeed, integrate HJS cats in their products (downpipe for instance for Fabspeed). HJS on their side, launched their own downpipes, with specific and dedicated dual chamber cat to have their downpipe to keep car ECE (EURO6 for M235i) homologated and CEL free. There is no integrated lambda spacer in HJS downpipe like it is in Fabspeed one for secondary lambda sensor. So NO, HJS downpipe and Fabspeed downpipe are not the same ones. I've a GFB DV+ and HJS EU6 downpipe and I didn't have a CEL since installed (+2500 km ago). But, first thing to do will be to read what error code triggered CEL. |
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09-08-2015, 02:55 AM | #19 |
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To my mind there is only one reference of HJS downpipe for M235i: HJS 90 81 2010
See this page for HJS downpipe products. Contact HJS Customer Service to ask them their distributor in Canada. Last edited by quenotte; 09-29-2015 at 10:14 AM.. |
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11-13-2015, 03:27 AM | #20 |
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I recently installed the HJS downpipe. So far so good!
Sound : increased volume of about 10%, more aggressive tone, backfire a bit louder and a bit more frequent. Perfect. Performance : pulls harder in low to mid rev range (less laggy) and it feels it wants to rev more. No check engine light. Here's a quick clip of the sound. Near the end of the clip, there's a shot of the exhaust sound with standard OEM downpipe for comparison. Very happy with this HJS downpipe. |
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