I use a 20ft whip line of smaller hose, it's not scientific but If I remove it from the 2 inch vac hose I don'nt notice a significant alteration in the engine rievs or sound but when I remove the wand I can notice straight away a difference in the engine, the same as when I remove the 2 inch vac hose from the filter
This tells me the whip line is not restricting the airflow top much as it would cuase the engine to strain more just like the wand
I made a 70 ft hidahose using 8mm thermoplastic hose, I did'nt notice any difference than normal hose in either vac power or heat loss but this was 8mm going through 2 inch vac hose with a big TM Blower