I've got a gx470 and looking at aftermarket crossbars for the factory roof rack, such as these options:
lfdoffroad.com
If using the included wind fairing, would I expect any additional wind noise, and/or worse mileage than stock?

Lexus Gx470 (03-09) Off-Road Roof Rack Crossbars Kit
GX470 ROOF RACK KIT The GX470 Crossbars Roof Rack Kit Is The Best Roof Rack Upgrade! This Kit Is 100% Bolt-On And Can Be Installed In 30min. The Kit Includes 4 Crossbars And 1 Wind Fairing. Made Of Steel And Powder Coated Black. Are You A Looking To Mount Your Mount Roof Top Tent, Hi-Lift Jack...
www.phalconoverland.com

Ruggedized Crossbar - GX470
Our Ruggedized Crossbars will bolt directly to your factory roof rails with no permanent modifications to your vehicle. The Crossbars provide a flat, sturdy mounting solution for carrying tools, off road recovery gear, cargo boxes, and roof top tents. Fully adjustable by sliding them to the...

If using the included wind fairing, would I expect any additional wind noise, and/or worse mileage than stock?