MODIFICATION STEPS:

At this point, you'll need to clean up any gasket material that was left on the engine block.  You should also have already cleaned up the new 89 lower intake and be ready to install it.  BUT!  Before you do, you'll need to use that JB weld that you bought...

If you look at a comparison of the 86 and 89 lower intake, you'll notice a difference:

The 86-88 lower intake has the "Port Air" entering the block at the outer engine housings, while...

The 89-91 intake has the "Port Air" entering the block in the middle housing, just below the two main intake ports. Notice the new manifold gasket in the background...  It has the holes for both.  I got this "universal" gasket from Mazdatrix.

So, before you can bolt on the new 89 lower intake, you'll need to block the port air in the center.  I mixed my JB Weld and let it sit for about 60 minutes...  Then I did a little spackle work.

Once that is done, you're set to bolt the lower intake back onto the engine.  (I'm not going to remind you to use the new gasket that you bought...nor am I going to remind you to make sure the 6-port actuator arms are lined up with the 6-port sleeves!)

Once you've got the piece on, you can reattach the two oil injectors, the 6-port actuators, and the ACV.

A note about the oil injectors:  There is NO vacuum source for the oil injectors on the front of the 89 intake manifold!  I installed new lines on my injectors and actually redirected the hose to the back side of the intake instead of the front.  There you will find a large vacuum source to hook up to.  (sorry, no pictures...)

THE MAIN FUEL RAIL:

Now that you've got the lower intake on, feel free to swap your lower fuel rails.  MAKE SURE you use new O-rings and grommets on your injectors.  Otherwise they will leak.  When your install the new o-rings and grommets, use a light coating of oil to make sure they seal tight and do not tear.  This is also a GREAT time to replace your rubber fuel lines.  Remember, do not ever use silicon vacuum lines for fuel lines...

Here is a picture showing the 89 injectors side by side with my 86 injectors.  In the middle is the old O-ring, upper grommet, and lower grommet: (PIC)

Here is a pic to show the 86 (left) and 89 (right) main fuel rails: (PIC)  I tried to fit the 86 rail with the new intake, but it didn't fit...

LETS GRIND SOME ON THE ENGINE:

You now need to start fitting the upper intake section that contains the VDI port.  This took a while...  First spot of concern is the 86-88 engine block has the "engine hoist" that has to be removed (PIC) and a small area of metal that needs to be removed as shown in the picture below:

The next point of concern is the old manifold mounts and the "Pressure Regulator Solenoid"  As you can see in the picture below, The old mount is not going to work and the orange solenoid has to be moved.

1)    Cut this bracket off (PIC)

2)    Remove the Yellow EGR solenoid... (But keep the solenoid!  More on that latter...)

3)    Move the Orange Pressure Regulator Solenoid to where the EGR solenoid used to be.

4)    Fix the vacuum hoses so they still match up to the pressure regulator, acv, etc...

5)    Bend the metal vacuum lines on the top of the engine block so that they do not touch the intake.

6)    Remove the large bracket from the engine block that used to hold up the old dynamic chamber...  and get to work cutting, grinding, and drilling it to fit the new intake...  (PIC) (PIC2) (PIC3) (PIC4)

 Once that is done, you're in the home stretch...You'll need to bend and twist a couple of small things to make sure the upper intake fits properly.  Once you're sure that you've got it, you can move onto the the throttle body...

THROTTLE BODY:

The 86 throttle body has a nipple cast into the bottom that hits the VDI chamber:

Here is a picture of the removed metal: (PIC)