Cali is screwy for lots of things but other times they do things for good reason like the one posted on Siliconeintakes site:
People always ask us why it took us so long to add boost/vacuum hose to our product lineup. Well the answer is simple:
MOST AFTERMARKET SILICONE BOOST/VACUUM HOSE THAT YOU CAN BUY DOES NOT WORK!
It took us some time to find a way to deliver a boost/vacuum hose that lives up to our high quality requirements. Most aftermarket silicone boost/vacuum hose that you can buy is too thin to carry vacuum! It will collapse under vacuum causing a wide array of problems, including high emissions, incorrect gauge readings, poor gas mileage, and possibly even engine stalling. Finally, we are able to deliver this super high quality silicone boost/vacuum hose with extra-thick walls, providing increased resistance to collapsing under vacuum.
aftermarket boost/vacuum hose
Our Silicone Boost/Vacuum hose has extra thick walls to prevent collapsing under vacuum.
Thicker walls also make our hoses more resistant to nicks and cuts.
Smooth, slick, shiny and easy to clean, this is show quality hose.
Substantially more resistant to cracking or fading than regular rubber engine bay hoses.
Higher heat and chemical resistance than regular rubber engine bay hoses.
When people first started using cheap silicone Cali obviously reacted quickly and haven't changed their minds even though the better quality hoses have come out.