The intake, exhaust and fuel modifications are minimal and simple to do. The most simple part is the intake system itself, for that stuff I am using a Z3 3.0i intake box, MAF and intake elbow(s)
For the exhaust you can just use the stock S52 headers on the M54 and it will bolt to your stock midpipe and be plug and play. The M54 catalytic converters are built into the headers, the E36 has them in the midpipe - running stock S52 headers on the M54 therefore makes it a neat plug and play solution which does not compromise the functionality of the catalytic converters
Fuel can be done very easily by running a long hose between the two open nipples pictured below (the nipple on the rear of the filter, with a small section of fuel line on it and the metal fuel line running parallel to the filter). I chose to spend an extra 10 minutes and do it "properly" ...the below pictures show the M54 fuel filter sitting in place among the stock E36 fuel lines
Above the fuel filter you can see a fuel hardline which does not have a corresponding feed line. On the stock S52 fuel filter setup the fuel filter receives one fuel input, the fuel pressure regulating valve and return line is on the output side of the filter and returns fuel to that now-empty hardline
The M54 fuel filter has the fuel pressure regulating valve built into it (the vacuum line nipple is the thing sticking out 90 degrees at the output) and the return line comes out the "input" side of the filter. A very easy, elegant solution for this is to source an extra E36 fuel supply line, which is designed to terminate at the input side of the filter. The M54 fuel filter inlet is the one offset to the side, whereas the S52 filter has the inlet in the center. So I disconnected all lines from the filter, loosened the clips that hold them on to the chassis and moved the fuel supply line over to where the return line used to sit, which makes it align perfectly with the M54's inlet. I then removed the E36's fuel return hardline and put another E36 fuel supply line in it's place, which let it align perfectly with the fuel filter return/outlet. This is very easy to do as well, since the fuel hardlines only run from the filter to right in front of the rear wheel (where they terminate into soft lines). You can also leave the fuel supply hardline in place, replace the return line with a supply line and re-arrange the soft rubber lines at the back to switch their orientation. I chose to pop it out of the clips, as the rubber lines tend to be pretty stuck on
In front of the filter - simply remove the extraneous fuel supply hardline. Later, I ended up clipping the M54 plastic vacuum supply line (for the fuel pressure regulator valve) into the open clips where the fuel return line used to sit. The rubber fuel supply line to the engine itself should be replaced with one for an M54, just remove the clamp at the base of the S52 fuel supply line in the engine bay and replace with the M54 style quick-connect hose. I used one from an E39
I chose to add long tube headers which was a little bit of work. I didn't take as much out of this engine mount as it looks like but the first step to fitment was getting it to fit around the engine mounts... its a tight fit.
They sure look good!
Once the headers were installed, the engine was installed in the car and bolted up
I had marked the exhaust roughly where I knew it was going to sit and got cutting... I hate cutting these double walled exhausts. Got it done though and once everything was in it was time to get the car back up on the lift and see what I was dealing with
I started putting some stuff together and slip fitting it into place. The outer pipe was in a fine place to start with, but the inner pipe sat way too low. So I ended up doing some measurements (thanks, Pythagorean Theorem) and cut a section out of the straight, angled section and added it to the edge of the inner pipe. Worked very well... had it tack welded in place (this was before I could weld myself and looking back on it, I don't think it was amazing work but it got the job done)
Then dropped the exhaust and had it welded all the way around on the headers and the exhaust.
That wraps it up for the exhaust