1) Are you going to install the Mk60 ABS unit from the M3?
2) You will want to spend the $25 or whatever on this program called ECUWorx so you can customize your settings and adjust your throttle mapping. Refer to the linked post here:
The S54 is one of the earlier adaptations of throttle by wire. It is a good system, but the stock throttle mapping drives me batty.
Normal mode/komfort mode throttle response is dead off the line and very flat, sometimes making you feel like you may stall the car if you are trying to get off the line very gradually. The rest of the normal mode throttle mapping is good and seems linear/natural enough.
Stock sport mode throttle mapping is insanity. Way too aggressive off the line and makes you accidentally slip the clutch if you aren't used to it/have been driving in normal mode for a while. The other reason I dont like the stock sport mode throttle mapping is it is so dead and flat near WOT, so when you are racing a Nissan Kicks SV for pink slips, teasing them along at 80% throttle and go for the WOT kill, you dont get 20% more throttle/power and can be disappointing. I have experimented a bit with the throttle mapping and tweaked it to something much more natural and enjoyable. Some people even tune it so WOT in normal mode is only 70-80% WOT as sort of an "eco mode" and then get 100% WOT only when sport mode is on. Fun idea, but ive had some hairball left turns where ive needed full steam ahead and need all of the beans in an instant.
What I ended up with turned out to be nearly identical to the throttle mapping on the Evolve tune. Since the MSS54 has dynamic timing advance, most tunes for the S54 wont do much more than adjust throttle mapping, remove top speed limiter, and will delete certain features that you ask them to. Some, like evolve will optimize the vanos maps a bit which is worthwhile, but a lot of the perceived gains are through throttle mapping, which is why ECUWorx is a badass little program.