[BMW Maniac]

I'm on bf.com monitoring your thread there too....I hate issues like this, especially after just being installed, so good luck to you.

With the idea of stock fuel lines being too restrictive...I'm not too sure you want to go that route just yet. The bottom line is, VF released this kit, ready to go as is. They would have noticed this issue and replaced the fuel lines too. This is a MAF based system, correct, and not a MAP based? If the engine runs lean at higher RPM, I'm either looking at some kind of air restriction going on, or perhaps the FPR/fuel pump cannot keep up and is failing.

The engine is seeing "x" amount of air, and is delivering "y" amount of fuel. "Y" is either correct according to the tune, according to what the ECU thinks the engine is seeing via the MAF, or what is limited by the fuel system.

Here is how I'd attack it and whenever I have problems on my turbo M3, this is my methodology:
1) Vac test.....usually, in boost, the engine will run rich because the accounted for air is leaking out in boost, but the fuel has already been provided...still, always check first and eliminate this as a potential issue...many people also want to assume away this problem...smoke test!
2) Fuel pressure check...what should it be idle, accelerating, in boost? Need to verify the fuel pump, FPR, injectors are all in compliance.

Good luck, and please let us know what you find out once this is resolved!