CAI that work?
 

I was just wondering if there is a cold air intake or short ram that is recommended? I believe that the stock air box is optimal and has it's own form of cold air intake, at least on the '07 etc. If not an aftermarket intake, is there a mod that can be done to the stock intake? I know that getting more horses with an intake is marginal at best, but better throttle response and sound are pretty nice too. Any thoughts are appreciated. I have heard that the Weapon R intake for these cars is pretty good but at $230 for no real gains, is hard to swallow.
Thanks in advance.

Price range for these units tend to be $200-260 thus need to work if wanting something lower cost.

If not in a hurry might look for used one, try Craigslist or Ebay. There seems to be a lot out there but may have search over time for one that fits your car.

Ebay also sells low cost bootstrap system parts such as air filter, plastic intake flex hose, etc.

Would avoid any filter using oil (washable) as don't think they clean as well as a paper filter and oil can get downstream to coat MAF sensor.

For 4-cylinder.

If looking for a change in sound might look at the resonator between intake and air filter.

Toyota added other sound dampening features after the cleaner such as another resonator, branch pipe, manifold shield. The 4-cylinder had a tendency to sound like a diesel at cold start in cold air thus these addition items may also dampen this noise.

Suppose one could insulate the air intake system as someone did to their truck in link below but this would tend to quiet it. In theory intake system air and air in engine compartment would exchange heat but how much temp rise between engine air intake and throttle body is unknown. May guess any improvement would be nil.

Insulating Your Air Intake. - FSB Forums

Thanks for the info and advice as always. I thought about trying to eliminate the resonator between the intake and air filter and the other one after the air filter but I am afraid of turbulence in the system. The last thing I want to do is hurt performance and/or fuel economy. I figure the toyota engineers are pretty smart but if removing resonators doesn't hurt anything, then I would be willing to try it. What are your thoughts about turbulence and doing more harm than good with resonator removal?
Appreciate your help as always!

If the resonator in front of filter, the air filter box and filter should straighten out the air flow before the MAF sensor. Good question as some CAI cause too much turbulence and with the box filter removed the MAF can have issues causing a check light or changes in MPG.

If the resonator after the MAF sensor, then the air is going into the intake manifold thus if turbulence it should not do any harm.

Resonators are just cans (cambers) that vibrate at certain sound frequencies (like blowing air over a jug) to dampen out the undesired noises (a counter vibration to the noise = undesirable vibration).

I doubt removing the resonator(s) and doing a good job securing the hole is going to result in any note worthy turbulence. Just be sure whatever you use to plug the hole is not able to be sucked into the system if doing this after the air filter.

Thanks again for all your help and advice. Now, any advice as how to remove the resonators and what to use to plug the holes? The one before the air box seems pretty large and integrated in the air intake pipe. Do you think cutting that section of pipe out (leaving actual air inlet scoop) and replacing with a straight hose or pipe would be best? Is there a different set up that would work better? I appreciate all your advice and time, thanks.

The resonator before the air cleaner is built into the air inlet pipe and can't be removed from the pipe?

I'm pretty sure the resonator before the air filter box is built into the pipe. I've seen a video on youtube of a guy cutting away the innards of the pipe to open it up. I guess I would have to look at the set up a little closer to be sure but I'm pretty sure it is integrated. Thanks, as always for your input.

Suggest limiting cutting on stock parts as if not satisfied with the results you can set back to stock. Perhaps look for a junk yard part to alter.

Agreed. Thanks again! I appreciate it.