I have not installed the TRD but, I've played with various CAI over the years and run a number of them on a dyno. I have however, seen the TRD system on a truck and spent some time looking at it closely. In my opinion, the new TRD system is pretty much a cool looking, expensive air box. On their web site, it shows one with a vacuum meter on it. It's the same one I run on my systems to tell if the air filter needs changing.
The air box's on modern vehicles are designed to flow the necessary amount of air. If your talking early 90's and older, those can be very restrictive and a better system is a must.
When choosing a CAI, the thing you need to watch for is, it must pull air from outside. Not all do and some open into turbulent air and actually can restrict at highway speeds. The TRD appears to pull from the same spot as stock. No loss or gain.
If the air filter is larger than stock you will get more life out of it and can run a more restrictive filter without suffering loss. High flow filters get that way because they flow, not filter. If the intake tube is metal, it gets hot and you lose power. The TRD I saw had a plastic intake tube and used the stock air filter. No loss or gain there.
The sad thing is, most of the CAI manufactures claim some incredible gains. That may have been true in the 70's. Most of the ones I've run on the dyno have either lost 7hp or lost part of the midrange torque curve. I don't see this issue with the TRD.
If your determined to get one, I would get the TRD. It appeared to be well made and designed to work with the vehicle properly.
Scott
