well like mike said, k&n has an open box design, so it is going to be pulling hotter air from the engine bay. the stock air filter
and box design is actually a cold air intake in itself. it is a closed box design and pulls cooler air from the passenger front fender well however the tube design breaks up the engine noise and make the air a little more hard to get in the engine.
the trd intake is made by Toyota Racing Development. hence id say they have better blueprints than k&n. afe is almost identical to the trd. if you want an intake that you truly get the most out of, look into the urd
intake. you have to do some cutting though...