Has anyone installed a cold air intake? Thoughts?

Many people have found no advantage other than a nice load noise.

 

There are lots of threads in various forums about installing cold air, warm/hot air intakes and the various results. Most agree that warm air intakes are better for efficiency, especially in colder weather. The intake system in your link appears that the filter would draw warm air from the engine bay as it has no source of cold fresh air from outside the engine bay (unless you plan on cutting a hole in the hood for a ram air scoop). It should be fine though, I'd say the difference would probably be too small to measure. Just keep in mind, it could cause error codes that kick the check engine light on and the dealer may not honor certain warranty claims due to aftermarket modifications. It doesn't look like TRD makes one for the Prius otherwise I'd say that would probably be fine with warranty.