Project E46 M3: Part 15 – more exhaust testing and weight reduction


Thus far, Project E46 M3's upgrades contributing to any weight reduction have come from the following parts:

D-Force wheels                           26 lb
Wilwood big brake kit                             1 lb
VAC Motorsorts headers                             5 lb
Megan Racing performance mid-pipe                          1.5 lb
Scorpion rear muffler                           19 lb
Optima Yellow Top D51R battery                           18 lb
Clutch Masters lightweight aluminum flywheel                        11.5 lb

Total weight loss to date: 82 lb

That's half a good sized girlfriend. We still have the factory electric seats in the car, and those porkers weigh a lot. Upgraded seats should easily get us over that century mark for total weight loss. Losing over 100-lb without taking out the AC, radio, or any sound deadening would be great. It's now a goal.


We mentioned earlier that the car baseline with the Megan Racing performance mid-pipe, but what we also hadn’t mentioned until now was that we refreshed the fluids on the car before doing so with Bavarian Autosport’s Liqui-Moly 10w-60 oil and factory Mann oil filter.

We also gave the internals a little cleaning with Liqui-Moly’s Engine flush, which you run in the car for 10 minutes at idle before draining it all.

The Mann oil filter comes with replacement O-rings, and you can also see here our magnetic drain plug we’ve been using throughout the years, which is also from Bavarian Autosport.

When compared to our baseline run testing the Clutch Masters clutch and flywheel combo, which also featured the Megan Racing performance mid-pipe and stock rear muffler (red), the Scorpion showed a little bit of flow up top to the tune of 3 WHP, although we think we could have gotten one or two more if we’d held this run to redline (it was cut 100-200 RPM short).

As tested with our previous Corsa and Magnaflow exhaust system, there isn’t a whole lot to be gained from a header-back exhaust system on these cars except for a different sound and less weight. What was interesting about the Scorpion versus the factory was the midrange difference—and these waves never changed.

If you look at area under the curve, especially with the low end, it’s in the blue line’s (Scorpion exhaust) favor. In any case, we think there is potential for a little more power with cam tuning through the BMW VANOS system after seeing this, which would be done through the AEM Infinity by Modified by KC. Stay tuned for that.

On the next page we've got a video showing the car's new exhaust sound.

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