I am just coming out of a Porsche Turbo. There are a significant number of ECU Flashes that range in price from $700 - $2,000. The price variation is largely based on upgradibility (stage 1, 2, 3) and customization but on the low end you can get 70HP for $700 which is a great HP / $ price.
As far as I know, there are not any pig tail options.
I am wondering if the limited amount of tuning options for the BMW is specific to the fact that turbo engines are so new to BMW and if we can expect to see some of the major tuners focusing on BMW based on the proliferation of Turbo engines in the BMW lineup ...