I got your answers here:
Injen Technologies Cold Air Intake System for the 2004-2006 Scion TC. This will not fit the 07 tC the Mass air meter has been changed. This intake featuring a two- piece design, which allows for a short-ram conversion if needed. We found that the Scion tC gains the best power by using the full cold air intake kit.
KEY FEATURES:
- Two-Piece design for ease of installation
- Tri- Step Process
- Able to convert to short ram
- Dyno Tuned Flange
- Gains of up to 12hp/9 ft-lbs of torque
The Injen intake we tested on our Scion tC test car had the best over all horse power of all the intakes avalible for the Scion tC. Check out the thread on Scion life here showing all of the dyno graphs.
http://www.scionlife.com/forums/viewtopic.php?t=92108
The Injen Scion tC intake beat out the other 3 tested by a total of 5whp which is about 6 or 7 total horsepower.
A Short Ram Intake which is often referred to as a warm air intake, positions the filter still inside the engine bay, but at a point as far away as room allows.. Although this Intake setup still takes in hot air, a short ram intake has less restrictions and uses a higher flowing filter allowing air to flow much more freely into your engine. The result? Depending on what you buy, about a 4-8 peak hp gain depending on car and other modifications. It may not sound like much but take into account that you will be gaining power from 2000 rpm until redline, meaning your car will be quicker everywhere in the powerband.
A cold air intake (aka CAI) typically has a longer pipe and its filter is positioned low in the engine bay, close to the ground where it can suck in the rushing air that has not been heated by underhood operating temps. Cold air intakes provide significantly larger gains then a short ram, on some applications gains of up to 15 peak hp have been recorded although this wont be the case for every car out there.