First of all, if you are confused about methanol injection, then you should read these articles:
http://speed.academy/methanol-injection-explained-power-gains/
http://www.hotrod.com/articles/how-to-boost-engine-power-with-water-methanol-injection/
http://www.stangtv.com/tech-stories/engine/get-schooled-water-methanol-injection-101/
Meth injection provides knock protection, cools the engine intake manifold, and allows for more aggressive timing in a tune. It can also add horsepower by allowing more boost pressure, prevent heat soak, steam clean your pistons, and keeps the turbo running at peak performance.
This installation was done with the kit from Eurocompulsion / HPSI, but is packaged with parts from DevilsOwn – it is a really nice kit. Mine may be slightly different, as I bought it used and made a few changes.
The first thing I did was mapped everything out – I chose to mount the tank and relay in the trunk, and put the rest under the hood. I already had constant power in the trunk for my sound amplifier, and there was also a ignition switched line to the trunk, used for remote power to switch the amp on with the ignition. (These installations can be found here.)
Before I installed anything, I had to prep the tank. The black part is a tank empty sensor – the plastic part floats, and when the levels drops, it completes the circuit. This can be drilled near the bottom of the tank, and the wires are run to a small red LED in my dash. The red and black thing is the check valve – this is installed as close as possible to the nozzle on the IC pipe.
This picture shows the spray nozzle that I tapped into the cold side IC pipe. I suggest removing the part, drilling it, and then clean out all of the shavings 100%. The instructions specify the hole size, as well as the size to tap the threads.
These lines easily run along the drivers door liner, underneath the plastic tray inside – there is plenty of room, and then into the truck. I used a distributor block for the constant power, mounted to the trunk. Here is the wiring diagram for the meth kit – I had to later change a couple of things to implement the solenoid valve for the factory boost leak.
The relay shows it needs constant and switched power, however, when I added the powered solenoid, it caused the pump to run constantly. It took me a minute to figure it out – The added solenoid closes the circuit, so I had to later modify the diagram above. BOTH PIN 30 AND PIN 86 OF THE RELAY MUST BE CONNECTED TO CONSTANT POWER.
It works fine if you just install the meth, but the boost leak needs this change, if you want the solenoid powered from the pressure sensor.
In the trunk, the relay connects to ground, and there are easy grounding screws behind the carpet – I mounted mine on the left side, and cut out the floor liner. This way, I can still access the spare tire, and under the carpet without moving the tank. I also had to cut a small slit behind the tank to allow the wires to pass through behind the tank unnoticed.
Cleaned up:
All of the connections were soldered and waterproofed, using liquid electrical tape. Two pins went to power through the distribution block, and one line directly to the pump (very short line) and then only one line needs to run under the car, all the way up to the engine bay. This line connects pin 85 and the pressure switch. You’ll want to connect this to the “NO” pin, or “normally open.” This line will also connect to one of the pins on the solenoid, also in the engine bay. It doesn’t matter which pin – it is easiest to crimp both wires together to the connector on the pressure sensor, and then waterproof it.
You do not need to use the NC (normally closed) tab on the pressure sensor for this application. You can see the brass T I’ve added, to give boost pressure to the boost gauge and the pressure sensor above.
This is the T that came with the kit – perhaps it works in the Abarth, but it wasn’t the correct size(s) for my installation: 
Use some heavy wire when you run the line underneath the car. There is plenty to tie wrap it up to, to keep everything secure. The line is also fused, to be safe. Ground the remaining pin from the pressure switch under the hood – there is an easy one next to the fuse box.
The pressure switch is connected to your throttlebody spacer (if you have one) or teed into the line for your boost gauge, if different. This has a thumb dial to adjust – set it to about 12-14 psi. I am spraying with nozzle #2, or 350 ml/minute, which is equal to 5.55 US gallons per hour. This can be adjusted to your taste and climate.
The second line in the pressure switch goes to ground, and can be purchased on ebay – I found it relatively cheap here. The second line of the solenoid goes directly to the battery, or constant power.
Use this search term in ebay if the listing goes away: “1/4 inch NORMALLY OPEN 12V DC VDC Brass Solenoid Valve NPT” Then I purchased two 1/4″ NPT to barb connectors from home depot, and inserted this solenoid between the cold side IC Pipe and the intake.
The evap system also tees into this line, so you’ll want to make sure you insert it before the T, or on the driver’s side. The direction of the valve is going out of the IC pipe, towards the intake.
I suggest you review this post by Greg from EC for more info.
The second factory boost leak was discovered by my good friend, Josh Cook ( @Jmcook321 on the .org ) tinkering with his engine. When he ran a boost leak test, he heard air rushing out of the separator. For $6.00 on Amazon, you can get a one way check valve that blocks this flow, in the line where my oil catch can is located, between the PCV and the intake manifold. (Search 10mm 3/8″ check valve.) I don’t have the numbers, but it is likely small gains on the low end RPM, and it is a very easy fix.
The arrow below shows the direction of the valve – all you have to do is cut the line, and insert this check valve – super easy!
The methanol mixture I use is from Walmart – the winter washer fluid. Most winter washer fluid is about 33% methanol – If you want 50/50 blend, you have to purchase “Boost Juice.” The stuff at Walmart is posted as $2.00 per bottle, but when I checked out, it rang as $0.50 per bottle – this may have been an error, but still a ton cheaper than the boost juice.
This is what EC recommends:
Meth party:
Completed Installation: