Our aluminum flange allows the 05+ sensor to be installed directly onto any size tube. The flange must be attached by welding. The radius on the flange is cut for 3.5", but welding will fill in any small gaps present when used on other tube sizes.
In 2005 Ford Introduced a new style of mass-air sensor. It is commonly referred to "slot" or "card" style. This sensor has no housing, the stock airbox has a receptacle for the MAF sensor.
We have found that the new sensor works very well in blow-through applications. Blow-through means the mass air sensor is placed after the compressor (supercharged or turbocharged vehicles). Slot style MAF's provide a very clean and consistent signal when used in blow-through. The slot style MAF can be placed in any size tube, from 3" to 4.5". We do not recommend going smaller than 2.75". In blow-through applications a 3" tube will result in your best signal, 3.5" tube will result in a marginal signal, and 4" will result in a very poor signal when used in blow-through. The car will need to be properly tuned for your new MAF sensor housing size.
When it comes to drivability and throttle response, blow through with an 05+ MAF is your best way to go. Having the MAF sensor far away from the engine makes the car harder to tune and hinders throttle response. In the past, tuners used to recommend suck-through, but this has changed with the introduction of the 05+ MAF. With blow-through the by-pass valve can now be vented to atmosphere. This will reduced air temps. The air is no longer being re-circulated and re-heated.
Running a MAF sensor in blow-through in a smaller tube than stock reduces range. To get this range back you can use a SCT or HPX slot style sensor. For very high power applications the SCT or HPX sensor is recommended.