I have a problem with this reply.
What you're saying is "trust me". "Trust me more than BMW. Trust me more than any figures I might come up with on a baseline run."
That's all well and good. Im sure you're an ethical fellow. But ethics aside, I want to see some hard numbers. If you don't trust your dyno to provide adequate baseline numbers (calibration or no) then why do you trust it to give modified output numbers? Do you have any hard evidence to support your contention that cars might run anywhere from 163-183 hp in stock trim?
To me it doesn't really matter what the car's stock output is. Show me that, then show me your improvements. If it's 70 over stock and stock is 163, you get a pat on the back. If it's 70 over stock and stock is 183, you still get the pat on the back. A gain is a gain is a gain. But let's see what the gains really are.
Show us the baseline.
-CW
Edit: I was just thinking, this works both ways.
If your baseline reads 160hp and your modified car reads 230hp, we celebrate.
If your baseline reads 180hp and your modified car reads 230hp, we still celebrate, just a little less.
But if your baseline comes in at 140hp and your modified car puts out 230hp, there's dancing in the streets and a Nobel prize nomination in the offing.
Isn't this reason alone to post it up?