lol, sorry for loosing you on the engine codes. I run down the basic ones.
M50TU- 2.5L I6 that is in M&M's car. TU stands for technical update, meaning it has VANOS
M30-Old school 3.5L I6 from the 80's till early 90's.
M52- 2.8L engine that is in the E36 328, E39 528, and E46 328.
S50/S52- 3.0L and 3.2L engines used in the E36 M3. 95 and 96 had the S50, 97 and on had the S52.
S62-mighty 394HP E39 M5 V8
S54-333hp 3.2L from the E46 M3.
S38B38-3.8L engine from the E34 M5. If you have seen Ronin and heard that engine wail (that one was actually a S38B36, the 3.6L) then you know how nice those sound. Listen here:
http://www.bmwworld.com/images/sounds/m5.mp3
Thats a quicky list of some of the more common, and best ones.
Here is a good list of them that I found:
http://www.bmwworld.com/repairs/codes/engines.htm
M3forum is pretty good even for non M cars, as most people there know a fair amount about 3 series, either through upgrading from non M 3 series to M3s, or b/c they drive non M cars. Good group of guys there, you'll get some good answers most of the time (webboards are always hit or miss).
I wouldnt go FI with a BMW engine. You can, and it will make good power, but the linear power in those is so great, that any boost profiles whatnot will only detract. A supercharger can help, but I guess being a total purist I see FI as going against a lot of the design philosophy. But then again, more power is a good thing.
I understand you now on the SA systems. I am not sure if any tuners use that or not, I really cant say. I know that from the factory BMW makes sure the part throttle and hp/tq curves lend themselves to effortless acceleration, and with VANOS makes sure you have the best it can give based upon the situation, regardless of throttle setting etc. Getting the best you can at any given time seems to be a hallmark of theirs.
Well if you are a fan of sweet handling, then you chose the right car. Most BMW's inherent trait is mild understeer, for safety sake. Almost all BMW's I have been in and around are like this, but, oversteer is easily available. The great thing about oversteer is that with the back of the car light (but not stepped out too far), you reduce your understeer. A corner taken full tilt in my old E39 meant that I wasnt countersteering or even steering neutral, I just had less steering dialed in to keep the back from going out farther. Less steering input = less work for the tires, and then less understeer. If you just whip the wheel into a corner, you will understeer, but if you know how to set the chassis of a car (by flicking it, trail braking, left foot braking, agressive turn in and then backing out some steering, lifting off the gas at turn in and then getting back on it, to name a few), then the car has the basic trait of almost pure nuetrality, with a oversteer a slight command away. It takes time to get good with a BMW, but once you do, they are heavenly. My boat of an E39 could take corners faster than almost anyone would imagine, even in a sports car.
I think the only thing to help out the non M cars is stiffen them up a bit. Most non M BMW's are a little soft by performance car standards, although they do stay pretty flat in corners. I know they could be stiffer for higher limits. But trust me, if it is your first time in or around a BMW, dont mess with the suspension till you can fully exploit it. Once you find the limits, then go for more; dont do it off the bat.
For the M cars, there are some wicked setups. ASC DFC is a nutty setup for the E39 M5, and is rumored to make the thing a total monster in the turns. Dinan does great work, and his S2 package supposedly makes the E39 M5 ride nicer than stock, while making it handle better.
Well, that should be enough for now, but as always, ask away. Sorry if I talk over your head, I'm kinda like Will Farrel in "Old School" during the debate. I start talking about BMW's go into a trance, and come out with a long string that might be hard to follow.