How do you get those kinds of speeds with Comcast??

Gotta have DOCSIS 3.0 Cable Modem with 8 channels. Something like SB6141.

Yep. Don't take ANY equipment from Comcast. I bought a DOCSIS 3.0 Cisco modem and a Cisco 802.11ac Wi-Fi router off eBay and everything has been working very smoothly. Seriously, if you want solid network performance, stay away from household brands and just get Cisco everything.

He signed up for their 'Blast' plan ;-)