8 inline

Am i really losing all that much cfm by necking 8 in inline down to 6in ?

I have an Amerifan brand 8" blower with a 8" carbon. On the intake side it has a 8" adjustable elbow with a 6x8 reducer. 6" duct running to a 2x4 tent. All three tents vents are open with the blower on the lowest speed.

It vacuums the sides of the tent in. I have to grab the flab door when unzipping it to open.

Have 8 in vivo sun pulling air through 6 hood then out into veg tent pullling air from veg tent through light in flower room and into attick. Wondering if i switched to 8 all the way through if it would keep cooler