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.
Cobb AccessPort - Tune First!
The tune is the only way to unlock the power potential hidden in your Focus ST. We highly 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 dial in custom maps from reputable Pro-Tuners and E-Tuners. These bring about the greatest gains and provide the most reliable increases in power. You can use the OTS maps while you get the parts they're designed for but after that, get a custom e-tune or dyno tune to make the parts and ECU swipe right on each other.
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!!
Intercooler Upgrade - Control Your Intake Temps
The upgraded front mount intercooler for the Focus ST is the number two power mod, second only because tuning is required to expose the potential of the colder. With the upgraded front mount intercooler, you will notice a massive drop in boosted air temps (we've seen up to 100 degrees lower!). And in case you didn’t know already, colder air is denser air, and denser air makes more power. Keep in mind that not all intercoolers are created equal. Cheaper cores will perform less efficiently and you will not get the bang for the buck that higher quality cores provide. Not only does an upgraded Focus ST intercooler provide more power, but the cooler air helps keep engine damage further away from a reality. Too much heat too often can really hurt long term engine performance.
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.
Rear Engine Mount - Reduce Engine Movement
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 for performance. 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 and Cobb Tuning rear mounts are two of the most popular mounts because of their 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. There are many options to choose from here. My recommendation is to get one that has a good amount of bushing material and the lowest durometer. In all my experience, my opinion is you just don't need an insanely stiff mount unless it's a race car. The softest bushing is a massive improvement from stock.
Exhaust System - Make It Sound Better
You can't deny having the right exhaust note singing in your ear as you go wide open through the gears. There are so many exhausts out there, we realize it's hard to choose from. We actually took the time to make some exhaust videos on our channel to show what you can expect. I love the Cobb and Greddy exhausts. They're subtle, punchy, clean, and visually appealing. But whatever exhaust appeals to you, just get one. We probably all love a great sounding car. Oh and some people say it doesn't add power but that's just simply not true. We've done the testing and they make more power. They become even more critical for making more power if you ever upgrade your turbo.
Bigger Turbo - Let It Breathe
Can you tell we're biased towards power mods yet? This list needs to have a heavy hitter on it. How could it be a top 5 list without the heaviest hitter? A big turbo changes your experience with the car. It's not just another mod that you sort of, kind of feel. If you've never had the pleasure of being in a 400whp Focus ST or anything like it, plan on your mind leaving your body when you shift at 7000 rpms in 3rd gear because that's where all the power is. Okay I'll slow down a little bit. There are a wide range of options here. I'm going to break it down as easy as I can.
The simplest, least expensive option we have is the Garrett Powermax. This doesn't get too much credit among upgraded turbos but it's one of my favorite. It's worth roughly 320-330whp which is about 30-40whp more than the stock turbo car with the same parts, so not a massive jump. But it spools exactly like stock and pulls much harder past 5500rpm where the stock turbo loses it's breath. Some people don't want 400whp, and that's respectable. There's more risk involved, along with more money. This is a killer upgrade and the easiest turbo to install. Oh ya and it's made by Garrett, one of the best and most established aftermarket performance turbo companies in the world.
After that, take your pick of 350whp+ capable turbos from ATP Turbo (Garrett), BNR, cp-e (Garrett), and Mountune (BorgWarner EFR). For sticking with the stock fuel system, my favorite is probably the ATP Turbo GTX2860R Gen2 kit. It spools great and will kiss the edge of the factory fueling limits. Perfect for using every bit of stock fueling power available at the largest rpm range. We have experience with our own custom EFR7163 kit and I would never tell anyone not to get one. EFR turbos are insane. BNR turbos are a great value that crank out great power and fit with a stock style downpipe and intake. And the cp-e Atmosphere kit is the best money can buy, a truly complete kit with options for sub-400whp all the way to 700whp+, all based around the same turbo kit parts.
This post was originally published in December, 2015 but has been updated to reflect current parts and accurate information!
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