BMW's strategy with my experience was to try everything first before replacing the fuel pump...But the truth of the matter is that software, plugs, fuel injectors are NOT gonna fix a faulty pump....the new pump along with the flash( BMW's answer to the problem along with the new HPFP) and the plugs, etc will be the fix, but the pump has to be changed with #43. BMW went to far last month with me on this issue as i had my car in the shop 3 times and FINALLY i threw a HPFP code and they changed it and all is good. My car has its mojo back, is fast , starts every time on the first crank but the experience left me pissed and resentful and i am taking BMW on over this...it's just not right...I still dig my 135i and want to keep it but you can only push us so far before we bite back. The problems with my HPFP started on my 3rd drive....and i no how you felt!!! It's totally un-professional and downright wrong.....in 30 years of driving i never experienced this on a car i just bought...but after 4 years in production the n54 engines are now possibly fixed??? For us and BMW's sake i hope this new fix is the answer and the cat's that have had to deal with this for years now is bizarre!!!!!!!
Lastly....even with this HPFP issue the 135i is a downright pleasure to drive, i LOVE it......trading down to a 128 although nice... will NEVER happen for me.....if anything N55 or M3 used...but never a car with LESS power!! Where is the fun in that.....i am looking at a 2011 Shelby GT though LOL.......