In FMU's words:
Take a look at our new rear section for the BMW E39 M5:
This system is made from 309 stainless steel and is fabricated by hand at Fluid MotorUnion in Plainfield, IL. The exhaust is installed by cutting the OEM rear section and replacing it with the FMU piece. Clamps will be included for an air-tight seal, and the FMU kit connects to all the OEM hangers for a perfect fit, just like OEM.
Instead of using mufflers, the FMU E39 M5 rear section uses one pass-through resonator for each tailpipe. With a typical muffler delete (that’s replaced by straight pipes), the resultant tone is raspy at best, and has a tendency to drone. The FMU’s use of resonators in place of the mufflers allows the true sound of the S62 motor to stand out, with the end result being a deeper, more aggressive tone at heavy throttle loads while maintaining a great amount of civility during both start-up and idle.
This kit is a great idea for those looking for a cheaper alternative than a full exhaust kit, and also for those who are wary of deleting the catalytic converters. We also opted to keep the tailpipe design similar to OEM for that stealthier approach to exhaust modification. It doesn’t have to look totally different to sound better. The retail version will come fully polished, as well.
There’s also the added benefit of a bit of weight savings, as well. Take a look at the size of these OEM mufflers:
And now check out the FMU system in the same car:
We’ve also made a video featuring Mike’s M5, the willing donor for the first copy of the FMU rear section. Aside from the exhaust modification, his M5 is 100% bone stock. No trickery here. Minus the "weight reduction" in the corner of the front bumper from unfortunate contact with what was left of a deer on the highway. Enjoy the video, and let us know what you think:
Since we’re very proud of our newest product release, the FMU E39 M5 Axle-Back Exhaust, let’s share some more pictures of the building process.
Whenever you’re working on assembling several smaller pieces into one larger piece, being able to visualize the final result is important. That’s why we lay out all the pieces for the axle-back exhaust in a row on the fabrication table. Or maybe it just makes for a good picture. It’s a mystery! …But it’s probably the latter of the two.
Whenever you’re working on assembling several smaller pieces into one larger piece, being able to visualize the final result is important. That’s why we lay out all the pieces for the axle-back exhaust in a row on the fabrication table. Or maybe it just makes for a good picture. It’s a mystery! …But it’s probably the latter of the two.
If you saw from the table picture, we pre-weld the tailpipes and the Y-pipe (prior to the double-resonator setup) based off our design jig, and proceed to assembly from there. We make sure the Y-pipe is cut evenly and prepped for welding to the single pipe that runs to the OEM midsection, and once that’s done we’ll tack the tailpipes in place (once again, according to the design’s jig, which lays out exactly how to build the exhaust such that the tips and all other parts will match up correctly to their corresponding spots on the E39 M5’s body).
And if you’re wondering what a jig looks like… Well, we can’t show you the whole thing, but below is a picture from the jig’s assembly process. As we mentioned, it’s a strict set of guidelines on where and how to arrange all the pieces of the finished product for perfect fitment.
Once everything is lined up in the jig, it’s time to start the final welds for the main parts of the exhaust (namely, the resonators, tailpipes, and connection at the axle):
After that, it’s back to the jig to finalize mount placement.
After everything is welded in place, we test-fit the exhaust system with the supplied clamps, in order to ensure a tight fit at all points, free of exhaust leaks or other pesky issues. We decided to use these specific clamps due to their smaller profile and their simplicity; rather than having to cut the OEM exhaust and weld on new flanges or v-band connections, this system lets you cut and then immediately clamp, saving you time and money during installation.
Once every part of the system is welded into place, we’ll test-fit it once more, just to ensure nothing has warped or moved around during the fabrication process. If everything looks good, it’ll end up in a box and on a truck to the exhaust system’s new owner!
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