Maf = measuring airflow inside a tube. Too big a tube, low end reads poorly, top end works well. Too small a tube and past a certain point you can no longer meter the airflow because the MAF has exceeded the voltage limit.
SD = measure the air with pressure and temperature using a set voumetric efficiency of the engine.
This is pretty much dead on.
The problem with large MAF intakes is that not only are they expensive but they also can cause drivability issues under closed loop (light load and cruising). Speed Density is free if you (or your tuner) are using either the Cobb Access Port or Open Source. The problem with Speed density is that it can also cause light load drivability issues if not done right/perfectly. I am not exactly sure why but I do know it has to do with how you fill out the Volumetric Efficiency, and also with fluctuating temps from heat soak and what have you (since SD uses temperature as one of the factors to figure out how much air is coming in). The fix for that is to move/place a temperature sensor as close to the throttle body as possible.
If your tuner is using Open Source you could ask him to use the MAF and SD blending, where the MAF controls closed loop and light load driving while the SD controls the Open Loop/WOT sections. This will get you the best of both worlds and not cost a penny. I am not sure if Cobb has it yet, but if they don't I am willing to bet they will soon.
Like you said, improper calibration of the compensation tables could cause some major headaches. However, the calibration of VE is for absolute pressure, so I don't see altitude being an issue if the car has actually been fully calibrated.
:shock: So much information! So running speed density would eliminate any potential problems with running to lean/rich due to temperature changes in the atmosphere?
:shock: So much information! So running speed density would eliminate any potential problems with running to lean/rich due to temperature changes in the atmosphere?
Like Oren says, two wires get soldered spliced. Read the cobb SD guide. And also, you're over thinking this. It's a sensor for temperature. Even spray doesn't matter. It's not a maf