I cannot recommend the AEM, I was a dealer of theirs for over 10 years but have gone away from that after numerous issues. Their harness options won't help you muh with a 318ti and they struggle with 60-2 crank triggering. It looks good on paper but the system architecture is dated and it shows when you try to use it.
This is what I do (
www.apexspeedtech.com) and I don't use this forum to promote my business, its about my personal car and interests. That said, here's my advice for you to consider:
1. ECU: The Link Atom II provides much better technical features, great technical support and is price-competitive with the EMS 4. If you can afford it, a MOTEC M84, its a good value.
2. Injectors: I only use Injector Dynamics. Paul Yaw is the injector guru. Don't take my word for it, google it.
Feel free to ask anything else.
-Neel