Second, it is clear that you aren't fully up to speed on SIR technology. It is not simply a 66% reduction in airflow like a 27mm flat-plate would be. [/b]
Of course I'm not, Andy. I'm an amateur mechanic and a club racer, not a aeronautical engineer. Anyway, I said it was a 66% reduction in the cross-section area, not a 66% reduction in flow. (You quoted it in your response, so I know you saw it.)

Any interest in having them send the before and after results, plus a description of the parts they used to install the set-up?[/b]
I don't know. Feel free to ask them.

We have ZERO letters from anyone telling us why 27mm is wrong, suggesting any 'corrections' in the context of SIR's, or helping us 'understand the issues'. Just complaints.[/b]
Conversely, where would I find information describing why 27mm is correct? I haven't seen any real help in understanding the issues; just assertions that it's correct, unbiased, and so forth.

Meanwhile, you've missed gone on about these other points and missed my most important question: I'm interested in hearing what other BMW racers are doing to prep their cars. As far as I can tell, just mounting the part requires custom fabbing duct work (to match the diameters of the SIR to the MAF), or finding a supplier who can make an SIR with the correct diameter. If I can find other drivers who are solving this same problem, it would help greatly; it's my hobby, and not my business, so having such a substantial workload dumped on me at the last moment is prohibitive.

In fact, at this point, I just can't imagine competing in ITS this year; I just don't see how I can get the fab work done, end up with something that works, aand so on, in time to have a successful season. Switching to a different class looks far easier.