Gunni - I have combo'd the Perfect Power unit with my M106 Turbo installs and they are a good combo. There, you get what you are talking about - full control over the fuel/timng maps via simple Windows software running on your laptop computer while the car is running. I sell custom implementations of this on my web site as a "Tuning Kit". The maf upgrade is not intended to be a tuning kit, as I have already done the tuning for the m42. It is simply intended to be a replacement for the old fashioned barn door.
Alpine003 - You're right. You do need to know a little bit about binary programming. Tee hee!
e9nine - Yes, you'll get more power. No doubt about it. But surely the power gains are not dramatic. 5-10 hp gains on a 130hp motor is not going to rock the world. Still, it is welcomed!
e30own'er - I'd have to custom tune your car in person, on a dyno.
bmwman91 - I did read your Maf kit exploits on the elctrical board. I hadn't seen it prior to posting my maf kit thing. Mine was done just because I produce these for other BMW motors and having fallen in love with my m42, I wanted to make one for it. I have a very good handle on the velocity curve design for the sensor housing based on my experience. And I have 2 CNC machines in our shop to make MAF housings and other parts. I will say only this: the velocity stack shape and size is very important! :-)
Euro Nation - you are definately right. If your current AFM is in top shape, you will not be well served to plop in an MAF kit. Although I have to admit, it looks great though, in the engine compartment!

Now I just need to clean up the rest of my engine compartment to match the looks of this new machined part. :-)
If anyone is interested in a combo kit combining the MAF housing and Perfect Power piggyback controller, let me know. I have a good handle on making those things work really well. I didn't do it for my M42 because it is all stock and I do not see myself needing laptop tuning control. However I have this setup on my M88-powered M5 and also on my old 83 745i and it is great.
This is a great board. Lots of good stuff.
My next project is to pull the entire suspention and brakes off the wrecked e30 M3 I have and put it all on my 318iC. Should be great as my shocks are totally gone on the 318. I am bouncing up and down all the way to/from work. I'll keep you posted!!
Happy new year.