Yup! That's the only way that kit works. Leave out one of the adapters but, then you lose air flow through the sloppy connection to the windshield vents.
Out of desperation one night I got on Nappa's website and after looking over the options for heater box hoses, I found the 2" and 2.5 " on their site. I ordered them in (6 ft lengths available only) and received enough to easily do two cars for less than the kit from DMT. Best part was I shared the cost with one of my friends and the hoses installed perfectly. Just had to use a little white grease on the hose ends to make it easier to install.
