If you've found yourself itching to modify your Ford Focus ST, there is tons of information out there on the subject and you may have learned plenty already. If you don't know already, the Focus ST responds very well to mods. But generally speaking, it only responds well to mods if you can tune for them. This is because the Focus ST’s ECU can learn and adjust to compensate for increased air flow. So if you are about to step out on the road to modifying your Focus ST, here are a few suggestions to help you get the most out of it.
Tune First!
The tune is the only way to unlock the power potential hidden in your ECU. We recommend the Cobb Accessport for the Focus ST as a means to tuning your ECU. The Cobb Accessport comes with Off-the-Shelf (OTS) maps that allow you to run many different performance parts safely and increase power as well. But its greatest contribution is the ability to flash custom maps from reputable Pro-Tuners and E-Tuners. These bring about the greatest gains and provide the most reliable increases in power. If you plan on doing different bolt on modifications over time such as intakes, intercoolers, or downpipes, you will be wise to hold off on the E-Tune until after all the mods are done. This will save you money in the long run.
Here is a dyno plot showing the difference between a completely stock, unmodified and untuned Focus ST versus the same car after flashing a Cobb Tuning OTS Stage 1 Map that comes preloaded on the AccessPort. This is with 91 octane, pump gas. What a huge difference at 4,000 rpms!!
Bang for the buck!
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| Stock Focus ST Intercooler vs. CPE's FMIC |
The upgraded front mount intercooler for the Focus ST is the number two power mod, second only because tuning is required to unlock the potential of the colder and higher flowing charge air. With the upgraded front mount intercooler, you will notice the drop in temps of up to 100 degrees and in case you didn’t know already, colder air is denser air, and denser air makes for more power. Keep in mind that not all intercoolers are created equal. Cheaper cores will perform much less efficiently and you will not get the bang for the buck that higher quality cores provide. Not only does the mod for the ST provide more power, but the cooler air can help to extend the life of your vehicle.
Our Focus ST Project Car with the CPE FMIC Installed. We also removed the factory grill insert to show a little bit of the intercooler through the bumper and provide a little more airflow through the bumper.
Why so soft?
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| Cobb Tuning's Rear Engine Mount - Clean and Functional |
CPE's Stage 2 Rear Engine Mount - A more |
If you have spent any time at all in the Focus ST, you will have noticed that a hard shift between first and second or second and third will cause a loud bang. First of all, this is not the engine hitting the firewall but it is a problem. The super soft factory rear motor mount allows a ton of movement in the ST’s engine bay. Adding a stiffer rear motor mount can help prevent this movement and lock down the drivetrain to ensure smooth shifts and crisper throttle response. The cp-e Stage 2 rmm is one of the most popular mounts because of its ability to secure the engine without a ton of vibrations. Their unique design is a huge benefit to the enthusiast who wishes to keep vibrations at bay while increasing overall performance.
Form, function or both?
This section has been struck due to recent crackdowns on the environmental impact of certain modifications.
The Focus ST Downpipe is the number four mod on the list because it not only opens up the flow on the hot side of the turbo, but it also provides a deeper more aggressive tone to your exhaust. Because of recent crackdowns, we can no longer recommend modifying this part, and we will not tune any car that is running a catless downpipe. Both catted and catless downpipes will net you a noticeable increase over stock with the appropriate tuning, especially in the middle of the rpm range. The Focus ST comes with a small, restrictive turbo from the factory and helping it flow more efficiently is one of the most reliable ways to make more power.
The CPE downpipe, installed.
WaaPSSSH!!
Focus ST performance mods are certainly not difficult to come by. There are plenty of aftermarket performance parts available and one of the most popular is the Blowoff Valve. The Focus ST factory bypass valve is small and plastic and located in the turbo. It is a very simple process to replace this diverter valve with an upgraded blowoff valve. Most people perform this upgrade for the sounds it makes on the on/off throttle transition, the undeniable turbo woosh. However, most people don’t realize the performance benefits of this. An upgraded blowoff vavle can extend the life of your turbo by helping to protect it from turbo killing surge. The blowoff valve 
can also allow you to run higher boost more consistently without worry of failure or leaking. The Focus ST Blowoff Valve is another think ahead mod though because while you can upgrade just the valve in the turbo, you could also delete/block off that valve and run a full size blow off valve in the charge pipe. This decision is made based on your future goals. If you intend to upgrade the turbo at some point, this should sway your decision to the charge pipe mounted blowoff valve over the stock replacement since this will be necessary to run the upgraded turbo.
Want to know more about modifying your Focus ST? Download our MODIFICATION GUIDE. We'll walk you through all the major modifications on a basic level and help you understand what certain parts do and why you might want them.
