Jose, OP has a normally aspirted engine.
And, with respect, I don't think you are undestanding what is happening when a turbo heats up the incoming air charge as it compresses it and builds boost and then tries to cool that air back down with the intercooler. Intercoolers are not anywhere close to 100% efficient, and air in the engine bay is much hotter than ambient (outside air).
I must respectfully disagree with your overgeneralized statement that CAI's are either worthless or a waste. Boosted cars need the coldest air charge possible. Ambient temps and underhood temps are greatly different once the engine gets up to operating temperature, especially when the car is sitting in traffic. And even more so after extended driving on boost with resultant high exhaust manifold temperature heating up the engine bay. That exhaust manifold reaches 1500 degrees F. It radiates that heat to the intake side via the closed environment with the hood down.
Now think about this: You lose about 1% of your horsepower for each 10 degree increase in temperture at the filter. The engine draws this air, whatever it's temperature may be, through the MAF sensor. Cold air is denser and has more molecules per unit of volume. It's mass is greater. The MAF sensor (mass air flow) is doing just that - measuring the mass of the air to determine how much fuel to have the injectors shoot into the cylinder head to match the target air to fuel ratio being called for by the ECU. More air mass means more fuel. This means MORE POWER.
Now, consider that even if the intercooler were 100% efficient (and it's nowhere close to that), the compressed and heated up air coming from the compressor side fo the turbo cannot be cooled down by that intercooler to a colder state than it was when it entered the turbo. If the air was 100 degress going into the turbo, it will never be lower than 100 degrees after going through the intercooler. That is fact.
Ultimately, you can see that if air is drawn from outside the car at, say 70 degrees, but air in the engine bay is 100 degrees, this is a 30 degree difference. That same 30 degree difference shows up if you measure the temperature of the air coming out of the cold pipe of the intercooler. If you start with 30 degree colder air, you end up with 30 degree colder air going into the engine after the heat up (turbo) and cool down (intercooler) process. I'm just using 30 degrees as an example. The difference can be much higher.
I've measure the intake charge temps at ambient air of 80 degrees at the left front fenderwell and compared that at the very same time with engine bay temperature at the location of the MAF sensor. After only 5 minutes of engine operation the difference is 30 degrees and rapidly climbing. I have photos of those sensor readings posted on my profile page.
The Speed 3 has a series of horizontal air slots in the fender liner just in front of the left front tire. Most CAI's, and I know for a fact the Mazdaspeed CAI and the AEM CAI locate the flter one inch behind those slots to draw outside air into the intake tract. If outside temps are 80, I want 80 degree air going into the turbo, not 110 degree or higher air from under the hood.
That thirty degrees of air temp rise is 9% of your engine's power. This is very significant.
Well, some guys say, but air temps in the engine bay drop after the car gets moving, because fresh air is coming in through the front grill. That is true, but it takes anywhere from 15-30 seconds for that air flow to meaningfully drop down close to ambient, and it's still, even then, going to be influenced by that hot exhaust manifold. When at the drag strip or during an encounter in which you are going to go wide open throttle, the whole race will be over during that 15 second period of time.
There is not a single auto manufacture that uses short ram intakes as a factory performance upgrade. They all, 100% use cold air systems. It woudl be cheaper to use SRI's but they are using CAI's for a reason: Colder air simply works better.
You might want to consider visiting the Kenne Bell web site. They make supercharged applications for a lot of different engines, including complete superchargers and intercooler kits. They have accumulated a lot of research data on temperature changes and the effect those changes have on intake charge and power. It's all there for the reading. Bottom line is that they will not honor the warranty of their kits if the engine is running a SRI. They insist that the user run a true CAI, and they define what that is very clearly.
http://www.kennebell.net/techinfo/general-info/HotAirWARNING.pdf
Now, all said and done, under most driving conditions, the difference in the MS3 will be minimal, in ordinary every day driving with a mix of highway and city driving. But if you spend a lot if time in urban gridlock or stop and go traffic, or if you are concerned about having an edge at the dragstrip or in an encounter with another car, then you might want to reconsider whether a CAI with filter sitting one inch behind open air slots to the outside is a worthless waste of money.
