So couple of weeks back I made a custom heat-shield box for my SRI which also includes an air-duct to the Front bumper which feeds cold-air into it. Testing wise, compared to the original SRI + (pod filter) heat shield - air intake temps (on Torque Pro +OBD 2) readings have dropped. From 60km/hr cruise before averaged 30-35 (this is mid Winter) to now around 20-25 (still winter).
Heat soaking that occur from traffic (stop and idle) - On SRI would get from 45-60 (depending how long), now at averages 30-35, peaking at 45 if traffic is stuck for 5+mins.
Otherwise when on FWY, air intake cools down about 1 degrees every 20 second and levels at 20 degrees - at 3k RPM, pulls cooler air and air intake temps drops.
So what I did:
1) Cut old SRI pipe at the U-bend, getting a 90 degree pipe.
2) Measure the area of the filter , roughly the box should cover 15 * 20cm , with a depth of 15cm.
3)Cut + fold aluminium sheets (can be done with carbon fiber) - cutting out inlet for the SRI, and cold-air duct.
4)Assemble the box together and paint
5)Cover in heat-shield material (used exhaust heat-proof padding).
6) With a flexible air-duct pipping (I used 3") but was difficult to place it in (had to squeeze the air tube in some areas to push through the chassis), I recommend 2.5" most likely.
Feed the tube from the top, to behind the ECU breathing tube and between the AC pipe, to the small gap underneath the headlight, and in front of your tyres, this leads to front bumper.
7) Install box into area with cold air tube.
8) Install modified SRI
pics are here - realised ozcelica has size limits etc