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    • BMW E9X M3 exhaust system breakdown diagrams - Where the primary and secondary cats are, silencers, what an X-pipe replaces, etc.

      One of the first modifications many people install on an E9x M3 is an performance exhaust system, and while the exhaust system layout of an E9x M3 may seem like elementary knowledge to most fans of the M3, IND constantly gets calls from less experienced enthusiasts who are simply too busy to put their M3 in the air and have a look underneath. I find myself sending clients photos of various exhaust combinations simply to give them an idea of where all the components sit, and how each part can contribute to both power and sound.

      We shot some photos of an Eisenmann exhaust system with a factory x pipe still installed to give people a visual reference to each component that makes up the original x pipe. This way, enthusiasts that are new to the M3 can better understand the components they may be thinking of replacing.







      This article was originally published in forum thread: A quick look at the E9x M3 exhaust system layout. started by Nate@IND View original post
      Comments 29 Comments
      1. Yukohama's Avatar
        Yukohama -
        Very educational posts, Thanks IND! Click here to enlarge
      1. LostMarine's Avatar
        LostMarine -
        I was about to post a new thread, but this works even better.

        Can someone tell me if i can bolt up n aftermarket X-pipe to the stock rear section? if most of the power comes from cat delete, id rather get the x-pipe first and then the rear section
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        Can someone tell me if i can bolt up n aftermarket X-pipe to the stock rear section?
        Yes, as long as it is a bolt in X-pipe that uses the OEM mounting points and so forth.

        You can just delete your cats as well... I have the OEM pipe with cat delete so you can save up for a proper full exhaust and use that in the mean time.
      1. LostMarine's Avatar
        LostMarine -
        well, it would be proper eventually, just id rather have performance over the sound first, so X-pipe first, then rear mufflers
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        well, it would be proper eventually, just id rather have performance over the sound first, so X-pipe first, then rear mufflers
        That is why I stated ditching the cats is a good move for performance and then you can get the full exhaust later. Or you can get an X-pipe first if you want as well as long as you know what rear section you will get to go with it. Up to you but it certainly is an option.
      1. LostMarine's Avatar
        LostMarine -
        Yes, i do have all that planned. M3 modding isnt cheap though as im finding out Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        Yes, i do have all that planned. M3 modding isnt cheap though as im finding out Click here to enlarge
        Which is why most people mod 335's...
      1. LostMarine's Avatar
        LostMarine -
        you should make this a sticky. I know I have to keep coming back to it. would make it easier for other S65 newbs to know what is what, even if it only showcases 1 particular brand. Im sure the E9x M3 is about to get in the hands of more of the younger crowd since they are coming off lease. Hell, If I can afford one, Im sure the N54 crowd on mommy's dime is about to jump ship too..
      1. BattaM3's Avatar
        BattaM3 -
        Modding in m3 isn't cheap? Feel the pain!!
      1. LostMarine's Avatar
        LostMarine -
        lol,
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        you should make this a sticky. I know I have to keep coming back to it. would make it easier for other S65 newbs to know what is what, even if it only showcases 1 particular brand. Im sure the E9x M3 is about to get in the hands of more of the younger crowd since they are coming off lease. Hell, If I can afford one, Im sure the N54 crowd on mommy's dime is about to jump ship too..
        A sticky for this you think?
      1. LostMarine's Avatar
        LostMarine -
        it would probably be the least worthwhile or technical bit here, but good to see all the parts one is gonna change..
      1. Sticky's Avatar
        Sticky -
        Well we can stick it, no biggie.
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        what is the purpose of an x-pipe in an exhaust on an NA car? exhaust gas scavenging??
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by dzenno Click here to enlarge
        what is the purpose of an x-pipe in an exhaust on an NA car? exhaust gas scavenging??
        it equals everything out. it used to be an H pipe or X pipe, but ithink people have gone away from H as X works better
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        ya i read up on it...it equalizes out the backpressure from the two banks and we know how backpressure plays a key role in NA setups..i just don't know why its preserved on FI setups...for instance, most modded GTRs employ an x-pipe
      1. LostMarine's Avatar
        LostMarine -
        could also have to do with drone, at least somewhat I would think..
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        could also have to do with drone, at least somewhat I would think..
        man i'm in love with my car again after daily driving on a catless exhaust for a while...i just sold my AE catless exhaust and put back my stock catback (still using the AR catless DPs)...totally love it even though I know i may be losing what like 5hp maybe?
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by dzenno Click here to enlarge
        man i'm in love with my car again after daily driving on a catless exhaust for a while...i just sold my AE catless exhaust and put back my stock catback (still using the AR catless DPs)...totally love it even though I know i may be losing what like 5hp maybe?
        LOL! dude i felt the same way when i went back to stock exhaust last week! I was in love again with such a nice quiet ride. If it was XI I would have kept it Click here to enlarge
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        we get too caught up in squeezing out every last poney out of these cars and totally forget just how amazing they are with some less mods as well...i feel an aftermarket catback is a mistake on this car honestly...catless downpipes are fine and have gains and relieve considerable back pressure, but catback, you just gain in the noise dept, any hp gains can be attributed to just dyno error