Nice write up Sooty, real shame this isnt' available for the 135i.
I put a Dave F (KnN based) system on my M3 Evo and it used to make the most wonderful noise. Made me feel like I was driving a race car. In fact I still watch videos of my Evo on the ring now and again just to have that sound back in my life for a short time
Really pleased for you, your car is shaping up very nicely indeed.