The power steering system uses a Z3 power steering pump with N62 pulley.
This was the first iteration of the exhaust and how I ran it with the 4.4. It is a true dual all the way back, into E92 M3 resonators and X pipe and then dumping just past the mid pipe. This version sat a little too low right and dragged over speed bumps and it's way, way too loud like this. You can see it drops down at the transmission mount, in hindsight I'm not sure why I did this - but it was a mistake.
I never wanted to spend too much time fixing this exhaust because I knew the 4.8 had different headers and a 4.8 swap was always pencilled in for the future. Once I did put in the 4.8, the exhaust looked like this
Bank 2 does not have heat wrap quite yet
For the 4.8 version 2 of the exhaust, I cut the original exhaust at the front of the X-pipe and rebuild it from the header back with 2.5" pipe all the way out. The 4.4 version had 2" until about the middle of the transmission then upsized to 2.5" for the rest.
Version 2 you'll also note that it does not turn down at the transmission mount. It's straight all the way back and should tuck under the body properly like a factory exhaust.
Suspension consists of mostly all stock Z3 non-M components. I have aluminum E30 M3 control arms and Koni yellows with H&R's and an M strut bar assembly because the M strut bar is contoured in a way to provide better clearance where I needed it.
The E30 M3 control arms are a pretty significant weight savings of over 50%, a 6 lbs saving per arm in unsprung weight.
The Koni cut-a-strut's are for M application, but I used non-M strut bearings to maintain correct suspension geometry.
The rear has upgraded E46 M3 upper shock mounts as well as solid aluminum subframe bushings and brand new rubber trailing arm bushings. I went with solid aluminum bushings to mimic the usage of solid bushings on newer M models and to minimize the likelihood of trunkfloor issues by minimizing the movement of the subframe. The trailing arm bushings were kept stock rubber to try to minimize NVH due to the solid bushings.
The rear diff was swapped to a 3.15 Torsen unit, it was originally a 4.27 ratio which was insane during the first few test drives. I did a mild rebuild on it, slapped an M diff cover on it and painted it silver.
Quite happy with the fitment with the Koni/H&R's. The springs are designed for the M engine and the total weight seems to be pretty close to the V8 swap because the ride height is about identical to my M's with this suspension.
Eventually I will get around to rebuilding these Fikse FM-10's. The rear has about 1" spacers and I plan on buying new barrels that are 1" deeper in the rear.
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