Thank you all for the input gentlemen.
I contacted Librands, and they've told me there's only 1 exhaust version available for the S1, the one with the 4 round pipes.
I know I will get chastised for this comment... but!, I personally find the Librands rear exhaust to be a much fuller, robust sound.
That's what I thought based on the soundvids.

Was afraid to get banned here.
I wouldn't cut the wings of a Series I to accommodate side-pipes.
You have a valid point, Aeroman.

I think Librands have a new customer on the way.