Installed APEXi Air Filter
The stock air box is good but it is a PITA to remove, and about everything you do requires you to remove it. Plus, when you start to upgrade it will start to be an airflow restriction. So replacing it with one of the after-market ones is a good performance mod. The only down point is that now you are pulling in warmer air from the engine compartment. This can be solved with a custom made box, but I am not worrying about that at this point. Also after you install it you can now hear the sucking sound of the air and your BOV when it vents, woooosh. Which is both cool sounding and a good way to tell if it is stuck open or close. If it is stuck open you will leak boost pressure, if it is stuck close you can destroy many expensive things when the pressure wave from the throttle plate closing under boost hits the intake turbine. This install should take about 45 minutes if you don't have trouble getting the accordion hose off. After that it is easy. There are many different brands of filters, HKS and K&N. I don't like HKS because it seemed to be a low quality wet-style filter and tested very poorly in a test done in Japan. The K&N is the most popular among Supra owners and tested well, but I choose the APEXi because it tested the best and I got a good deal on a new one.

Tools: Phillips Screwdriver
  10mm Box Wrench
  10mm Socket Wrench
  Pliers


Part Number Reference Chart
Toyota Part Part Number Description
Air Cleaner Hose 17882-42012 Accordion Pipe
Ventilation Hose #4 12264-42010 Short hose to PCV system
Air Hose #2 (for ISC valve) 17348-42010 Long hose from Accordion Pipe
Auxiliary Air Valve 17670-42010 BOV
Auxiliary Air Valve Hose #1 17341-42070 BOV to 3000 Pipe Hose
Auxiliary Air Valve Hose #2 17342-42040 BOV to Accordion Pipe Hose
Auxiliary Air Valve Hose #3 90445-10022 BOV Vacuum Hose
Hose #1 (for Idle-up) 90910-05186 Vacuum hose on bottom of Accordion
Air Flow Meter Gasket 22275-42020 Rubber Gasket at front of AFM


Teardown
1.   Using a 10mm socket wrench loosen the hose clamps at the 3000 Pipe and fender connections. Remove as one big piece.
2. Remove the upper IC hoses.
3. Remove the two 10mm bolts that hold the front air box to the frame.
4. Remove the 10mm bolt that connects to the brace off the AFM.
5. Disconnect the AFM electrical connector.
6. Using the wrench to first move the hose clamps, then disconnect the 3 air pipes to the accordion pipe.
7. Loosen the Phillips screws for 2 hose clamps on the accordion hose.
8. Push the front of the air box towards the front of the car then compress and pull back the accordion hose until you can slip the rear side of air box up past the front part.
9. Disconnect the PS vacuum hose on the bottom of the accordion pipe.
10. Pull the Accordion hose off the turbo.
11. Remove accordion hose and rear air box as one piece.
12. Remove the front air box.
13. Separate accordion hose from AFM body.
14. Inside the rear air box, pry back the tabs on the lock plate that cover the 4 brass bolts.
15. Using the 10mm socket wrench remove these 4 bolts.
16. Remove the lock plates and the brass air cleaner cover.
17. Now carefully separate the rear air box from the AFM. There is a rubber gasket in between. Mine was stuck together so be careful when pulling apart that you don't throw a piece across the room.


While you are here
1.   Accordion Hose
After years of being in the engine the accordion hose can get brittle and cracked. Especially with the stress it takes being put on when you still have the stock turbo. The good news is that I found it was only $30 to replace. So even if yours isn't cracked, if it is old now is a good time to replace it.
2. Accordion Hose Air Hoses
The various air hoses, 3 of then, that come off the accordion hose get very hard in there old age. The one to my BOV had to be chiseled off after 12 years. It makes life much easier, to take them on and off, if you replace them with soft versions. You can either get them at Toyota, for about $20 each, or go to your local auto parts store and find something similar.
3. Accordion Hose Vacuum Hose
I found that this little hose was also a PITA. It was hardened and too difficult to remove so I just cut it off. It would probably be easier to just cut it, instead of removing it, and replace it at this time. It is just a simple bit of vacuum tubing so is less than a buck.
4. BOV
While things are off your car take your BOV and see if you can blow through it. If you can it is, like mine was, toast and is leaking your boost. You can buy the one from Toyota but those are expensive. There are two other options that I know of which are to use the BOV from a SAAB or Porsche and are $25-$30. There is a SOGI tip on installing them, as well as one from my own install. This can be done at another time because the BOV is easy to remove.


Assembly
1.   Air filter on housing. Attach APEXi filter to APEXi supplied housing.
Using the four supplied bolts, I didn't use the extra supporting bracket that they supplied, place the blue gasket between the filter and the housing and lightly tighten the screws in the holes. Then slowly going around tighten down the screws until they are snug. There is no specific direction at this point, but if you care the APEX stamped portion will be facing up-ish after you are all finished.
2. Put the rubber gasket back on the AFM if is not already there. Mine was still soft after all this time, so if you don't rip it taking it off, you really don't need to replace it.
3. Air filter on AFM. Attach APEXi housing to AFM
Place the air filter section on the AFM with the word "APEXi" on the housing on the same side as the AFM electronics box. Using four of the supplied nuts loosely tighten down the housing no the bolt studs. Now using the 10mm box wrench go around tightening down on the bolts until they are all snug.


Reinstall
1.   Place the accordion hose back on the turbo.
2. Reattach the 3 air hoses on the accordion pipe and use the pliers to secure their hose clamps.
3. Reattach the vacuum hose to the bottom of the accordion pipe.
4. Put the air filter/AFM assembly in filter first then slip the accordion hose over the AFM.
5. Bolt the AFM bracket back to the body with a 10mm wrench.
6. Tighten the two hose clamps on the accordion pipe with the Phillips screwdriver.
7. Reattach the electric connector to the AFM box.