This write up is not for the common user. If you are not completely comfortable doing every other modification on this site, then I would not suggest you do this yourself. We will be modifying the ECU, fueling and the entire turbo system. An error in the installation could permanently damage your engine. If you feel that you are not very strong at DIY work, then just read this for the knowledge.

With that said, this guide is not made to be completely comprehensive. The main purpose is to show the steps needed. Since every car/kit is different, you will have to use some of your own ingenuity to figure it all out. If you start out the install, and get half way through and get stuck you could end up in more trouble than you bargained for. You should carefully inspect the current setup, and take a lot of pictures of the uninstall of the stock turbo before you proceed. It will be very easy to forget where everything goes if you don't write it down and take pictures.

Ready?

SUPPLIES - At this point, you are a modifying machine - so I will assume you have all the tools you will need for this job. You MAY need to do some welding depending on your setup. I suggest you use PB Blaster or Liquid Wrench on EVERYTHING that gets hot in normal use.... it will save you lots of time. At this point, if you are considering this upgrade, I will assume you A4 is already equipped with the following at a minimum:

Front mount intercooler or dual side mount intercooler's -(RaceTec FMIC)
Upgraded race clutch - (Southbend OFE SS)
Full Cat-Back exhaust - (Neuspeed Cat Back)
Upgraded brake and suspension systems (B5S4 Brakes, Neuspeed Suspension)
Boost Gage
Vag-Com software and supporting cable

If you do not have these supporting mods - you are only asking for trouble. Get your car in shape before you spend the money on the turbo upgrade.

I am also going to assume you checked your car out, or brought it in for a check up to make sure it is in good running health. Any pre-existing problems will become worse with a big turbo upgrade.

As with any large installation job, be sure to be very neat with all your nuts and bolts so that you know where they go when you reassemble everything

In the first part of this install you will have to get the car down to the point at which you can pull the turbo. Because there all of these steps have been outlined elsewhere on this site, I will point you to the links of where to start. Perhaps when I am not as lazy, I will add all these parts to a single write up.

First - remove the front bumper: See Front Bumper Removal
Next - Remove the stock air box: See the bottom of the Neuspeed Exhaust Install

With these two steps done, you will be somewhere around here

From the air box there is a hard feed line to the Secondary Air Injection (SAI) pump which is located below your passenger's side headlight. Coming back front he SAI pump is another hard line that runs across the top of the engine.

You can see that the Turbo Inlet Pipe (TIP) has two air connections on it. One is circled above as the PCV return valve. The other is for the Diverter Valve (DV) or Blow Off Valve (BOV) and is not visible in this picture but can be seen from underneath.

From this point, you can go ahead and unbolt the CAT from the turbo. Some of the nuts are hard to reach, but you can use swivels and extensions to get at them

Also unscrew the front O2 sensor from the Cat

To pull the cat, you still have to unbolt if from the exhaust system. To do this, first unbolt the CV boot heat shield over the passenger side CV boot. There are 3 hex head bolts.

Use a hex head attachment for this - not an allen key.

The heat shield is shown here, as are two of the three bolts you need get at for the cat

The first time I took these bolts out, it was a huge pain, you can read about it in the Neuspeed Exhaust Install

After the cat is unbolted, you can take it out from the top

With the Cat out you can start to drain the coolant and oil. In some cases (where these lines are not replaced) you can get away without draining the coolant - however I decided to flush the system.

To drain the coolant, look for the Coolant Sensor on the driver's side of the vehicle down below the headlight. There is a clip holding it into place. You remove the clip and pull the sensor out. The coolant will start pouring out - so have a bucket ready

The next step is to remove the stock turbo inlet pipe. You will have to disconnect the PCV valve and the hose for the diverter valve. You can get the PCV from the top, and the DV from the bottom

PCV valve has been removed here.

I don't have a good pic of the DV connection, but you will see it once you look. I am sure the picture is elsewhere on this site like in the FMIC install or the BOV/DV install

On the TIP you will also notice a smaller connection which goes to the N75 valve (which looks like a black "T"). This also needs to be disconnected.

With the N75, DV and PCV disconnected, you can unscrew the hose clamp that holds the Turbo Inlet Pipe (TIP) to the turbo (bottom left). With the TIP out it will look like what you see in the picture below and to the right

You should take note of the oil and coolant feed lines to the turbo. I will be replacing these, but you may not have to. In BLUE is the coolant feed, in RED is the oil feed.

Move the appropriate oil and coolant buckets under the turbo, and unbolt the turbo oil and coolant feed lines. Let everything drain

Be prepared for a mess.

Next get under the car and disconnect the oil return line

And then the coolant return line. Be prepared for more spillage.

With the oil (feed and return) and coolant (feed and return) lines disconnected, you can now pull the manifold/turbo assembly by disconnecting the manifold bolts.

You've used PB Blaster on these right? Or maybe some liquid wrench? You will notice how shiny everything is in mine... because it was covered in PB Blaster. Made life much easier.

After these bolts are out, you can pull the assembly,. and see how small it really is...hah

Now that the old turbo is out, you can take this time to remove whatever lines you will be replacing. In this case, I had to remove the stock oil feed line.

This line is a hardline that runs around the back of the block and connect to where the oil filter is. It has many small nuts and bolts holding it in place. Instead of showing all this, I only show one picture.

Note the Banjo bolt at the oil-filter end

I installed the turbo to the manifold outside the car, then slide the whole assembly in just as I took the old one out. It takes some adjustment, but it will go.

Just rest the manifold/turbo on the studs off the engine. Do not bolt/tighten anything yet. You can put a couple nuts on a couple of threads, but don't bother with anything else. After the oil and coolant lines have been run, you will need to pull the turbo back for some room to slip the new APR TIP on the turbo

NOTE: After the fact it was brought to my attention that you can install the turbo/manifold AND Cat as a single assembly. You may want to try this on your install.

The first line I ran was the oil feed line I first connected it to the turbo, then ran it around the back of the engine (similar to the stock line)

Below you can see the route I took with it...as well as the connection to where the oil filter is. Note: If you have never used banjo bolts (or even if you have), you need two appropriate sized crush washer for each bolt - one goes on each side of the Banjo. If you do not have the right washers (too big) you will have a leak. Ask me how I know....

With the oil feed line in place, you can run the oil and coolant return lines. In order to make more room, it removed the useless boost reservoir that (used to be) connected to my turbo outlet pipe.

You do so by just unscrewing these three bolts and disconnecting the hose that takes this to your DV.

With the boost reservoir removed (green dotted line) you can connect the coolant return (blue) and oil return (red) lines.

Once again use the proper crush washer for the Banjo bolts.

Now is a good time to check out your old assembly. The N75 has three connections on it (its a "T") Take note of its orientation in the picture to the left and on your turbo. One side goes back to the Turbo Inlet Pipe (remember disconnecting that?), another line goes to the wastegate actuator....and the last line goes to the side of the turbo.... but wait a minute...

Look at the GT28RS.... that turbo doesn't have a connection for the N75!. Now we are at a crossroads... do you drill and tap the turbo or is there a better way?

Technically, all the valve needs is a 'boosted' connection to measure the amount of boost the turbo is putting out. Ideally this source should come from as close to the turbo as possible (otherwise you will be measuring what the turbo is generating minus the losses to get to the measurement point). Regardless, I did not feel safe tapping the turbo, so I decided to get this connection from my turbo outlet pipe....

At this point you will be very happy if you chose the APR FMIC with the kit. The kit comes with a turbo outlet hose that has a connection for the N75 and all is good. If, like me, you have another manufacturer you will have to make do with what you have. I have a RaceTec FMIC which happens to have hardpipe straight to the turbo (no rubber hose). So for me, some welding was needed. But I will get to that later.

Presumably, at this point, you have the manifold/turbo in place (bolted down) with the oil feed and return line and the coolant return line run. You also have the TIP in place. So now you have to plumb the diverter valve, the PCV system, the turbo outlet pipe and the N75. Unfortunately, this is the hardest part.

The APR aftermarket TIP does not have connections that are easy to access. They do not easily line up with the connections for the stock TIP. You will have to do quite a bit of plumbing to get it all to work.

I don't have any good pictures of how I plumbed these things but I can try to explain. At first, I thought it would be a cool idea to sit the BOV on top of the turbo inlet pipe. This would allow me to adjust it with ease.

I plumbed it this way, and it would have worked just fine - however I couldn't get a piece of the air box back on, so I had to readjust.

Either way, I will try to explain how I plumbed the DV

I fully understand that the picture above is awful, but it is all I have. Next time I am under the hood, I will get a better snap. Either way, I used a 180 degree turn around off of the TIP, then a female-to-female adapter (the red block) then another hose with a 90 degree angle in it. This was long enough to get the BOV between the engine and the radiator fan (note, the BOV is located lower than what is shown in this pic!) It is positioned like what is shown below

If you are comfortable in going forward with the rest of the install (not throwing in the towel), go ahead and bolt the Cat in place - using all new gaskets. The nuts from the Cat to the Turbo are NOT easy to get on, and you will have to use a lot of patience here. My buddy Chuck was much better at this than I am. I have no patience when it come to working in small places.

There was one nut (which is closest to the engine) that we could not get enough room to put on. To this day, I wonder how it is done.

We decided 4 out of 5 were on very tight (with loctite) so we didn't worry.

NOTE: If you install the Turbo/Manifold AND Cat as a single assembly you can avoid this

The APR Stg3 kit uses a 3 inch Mass Air Flow (MAF) sensor housing. As is, this sensor will not fit in the stock air box. However, with some small modification, it will fit. The first thing you need to do is remove the stock MAF housing. To do this, simply remove the two Torx screws and pull it from the box.

With the MAF housing out, you can see that there are spots which can be ground down to make room for a larger housing. Use trial and error and slowly grind the inside of the air box smooth to make room for the larger housing..

When it is done properly, the 3 inch MAF housing will fit in the box with little or no resistance

As mentioned previously, the turbo outlet pipe needed to be modified to work for this turbo. There are two reasons for this. First, the turbo has no connection to the N75 so one had to be added to the turbo outlet pipe to get this to work. Next, the GT28RS sits about 3 inches farther to the front of the vehicle than the stock K03 turbo. Therefore the hardpipe from the intercooler would not work as is. To modify it, I did the following

Before I went ahead and welded anything , I wanted to see if it would even be possible to get this pipe to work. In the picture to the right, you can see how far off it really was.

As it turns out, RacTec now makes their pipe as two pieces to allow more flexibility when fitting the intercooler. I contacted them and they indicated to me where they cut the pipe. I adjusted it a little bit for this application.

The first thing I did was cut the FMIC piping where the green line shows.... This was right on that second weld. This would allow me to add a flex elbow in that spot to give me the 2-3 inches of movement I required at the turbo side.

Here's what it looked like after the cut and elbow were put into place. The 2-3 inch gap was recovered.

You get another shot of my buddy Chuck that was helping me with the install.

After I knew the pipe was going to fit, I decided to weld the bung into place for the N75. I went to the local hardware store and bought a brass fitting that was barbed on one ended and threaded on the other.

I had my other friend weld a small aluminum spacer onto the pipe so that it could be drilled and tapped for the brass fitting. First I hammered an indentation of the spacer into the intercooler piping

Remember, you want to keep this connection as close the the turbo as possible!

After that was done, my buddy welded the ring in place, and it was tapped and the brass fitting was placed.

Note: welding aluminum is hard, so its not going to look pretty. However it does the job.

After that was in place, the intercooler piping could be test fit

Here's what it looked like from underneath

After the bung is welded on, you can connect the new connection to the N75, and plumb the hot side of the DV/BOV.

So now you have the turbo installed, the coolant and oil lines run, the cat bolted up, the FMIC piping modified and connected. The DV is installed, You modified the air box for the larger 3" MAF housing and can button that up. All that is left is physically installing the air box and then the injectors. Last, you can pull the ECU for it to get chipped.

If you have made it this far, I assume you will be able to re-assemble the air box and get that all together. Like I said, it is TIGHT, so you will have to have some patience fitting everything else in.

To get the injectors installed, check out the Injector Install Write up

For the ECU removal, check out the ECU Removal Write up

You should have everything you need complete. You checked all of your hose clamps so that the new turbo doesnt blow them all off right? That will be your biggest problem - just like it was for me.

Before you can turn this beast on, you have to prime the turbo. First you have to refill your oil and coolant (I am assumming you know how to do this). Then with the ECU Removed you have to crank the engine (clearly it will not start) for 10 seconds at a time for about 3 minutes. This will get all the oil through the lines and will get it primed. Keep an eye out for coolant and oil leaks. You should be good to go after that.

When you re-install the ECU, you will have to let the car idle for about 10 minutes. During this time you will see SMALL amounts of smoke coming up off the turbo. This is just oil from you hands and whatever else burning off. If it does not clear up quickly - stop and check everything!

Before you beat on your car, I suggest you follow typical procedures to break in the turbo and monitor your car closely (Air fuel ratio, etc) to make sure it is running properly. You don't want to come this far just to blow your engine.

Good Luck!