I use both a high end high gain 15db antenna on my wireless access point as well as a signal booster on my WAP as well.
I don't know which wireless adapter you use for you TiVo, but some wireless adapters allow you to use different antenna's as well. If you can, I would use a DIRECTIONAL
antenna pointed directly at you WAP.
In my setup. I put a high gain OMNIDIRECTIONAL
antenna on my WAP, & use DIRECTIONAL
antenna's on my devices. At least those that allow me to use my own antenna's.
I use Hawking Technology's
High gain antennas & signal boosters and can get almost 700' in some locations and through reinforced concrete walls as well.