I just got my car back from the Porsche dealer and I was a bit surprised to see the windshield they installed was not a Sigla (as my original one was), but rather a Pilkington. I figured since I (well my insurance company actually) paid $900 for a dealer-supplied windshield, then it would at least be OEM. The service manager showed me the invoice from Porsche which showed where they got it. I can't help but feel I got an aftermarket windshield for the price of the genuine article. But hey, I guess I can't complain too much since the view out the front is superb.

maybe ok
 

I believe sigla was originally a pilkington company or brand.

"Classic Windscreens from an Original Source
Pilkington Automotive offers short run production of classic windscreens and special parts from its factory in Queenborough on the Isle of Sheppey in Kent. In many cases, the original classic cars were built with glass from a Pilkington company eg Triplex, Sigla, Bilglas, SIV brands, and we can still supply with the original trademark."

It is interesting they did not use the original SIGLA trademark on this windshield if SIGLA was in fact a Pilkington company.