I wish you guys would stop referring to the 2, 2" hoses being called 4 to the door. That's the stupidest setup, and it's a waste of time. Just keep your wand locked on the carpet for more lift to carry that water back to the TM WITHOUT ANY PAINT FILTERS. Let the basket do it's job. Your suction will remain stronger for a longer period of time. The sand will go through the basket and fall to the bottom of the tank, taking longer for the basket to fill up.
Now, back to the hoses. Time is money. Either run one 2" hose or ONE 2.5" hose, depending on the blower size. NO MORE. Just get the job done.
for years, I tried to overthink this job. Wasted a lot of time, AND MONEY, experimenting with all the tricks and SECRETS, of our trade. The jobs took longer, and profit was down.
Find your groove, and stay with it. Is the carpet coming clean? Are your dry times under 8hrs? Good. That's all you need.
And get out of the stupid 4 to the door idea.