N63 Only Perf Mods - your experience?

[Craigas]

Hi I'm new to the site, just bought a 2012 650i X-drive coupe. Loving it so far, very nice car, think I stole it from them as it has only 27000 kms, and I plan to drive it that way

Being a bit of a motor head but new to the world of turbo tuning was hoping to get some feedback and advice on mods. Done a bunch of reading so far and this is what I have learned.

Motor is known as a N63 and as such has about 400 HP and 450 Torque, has relatively high compression for a turbo motor and hence is somewhat limited in pushing the tuning too far without dealing with the octane problem. Different turbos are generally a non-starter for various reasons (where to source Alpina??).

Anyways, back to the thread. Would like to build up a post of other members experience in the three stages of performance listed below, your parts list, your experience, pitfalls, etc.

Overall the criteria MUST BE (N63) and retain the beautiful driveability when not on the pedal.

Stage 1 : Target 450/500 Approx (HP/TQ)
Criteria: 93 Octane, no bolt-ons, tuning only

Stage 2 : Target 480 / 550 approx. (HP/TQ)
Criteria: 93 Octane or with additive, no bolt-ons, tuning only

Stage 3 : Target 500+ / 550+ (HP/TQ)
Criteria: Bolt-ons OK, water injection, etc

Stage 4 : All out - new turbos, etc

I know this forum doesn't have a lot of people that modify their 6, so I'll be patient In the meantime I'll continue to do my research

Thanks in advance, would love to hear so stories of how you progressed through the various stages as well.

Finally, has anyone done water injection and able to run 93 pump gas? What numbers were you getting?

Craig