Ford Focus RS Power Modifications and Tuning


The Ford Focus RS is the hottest $40,000 car around right now. A new addition to the rally car segment in the US, it takes on the STI, the Golf R, and the echoes of Evos past. All things stock, the Focus RS seems to have them all beat, outgunning them by around 40 or 50hp, but what happens when aftermarket mods and tuning come into play?

The simple fact is the Focus RS’s stock turbo is out of breath around 380-400 crank horsepower on pump gas. Ford doesn’t use way oversized turbos in their cars, and as a result its basic tuning potential may seem a little lacking compared to, say, the Golf R or the Evo.

Having said that, fear not, because peak horsepower numbers are only a small portion of the story, especially for a street-driven car. So let’s have a look…


Note: Focus RS’s need to be dynoed in FWD mode because their AWD system gets confused on a chassis dyno. Most tuners are giving their WHP gains in FWHP, however I’m going to approximate AWHP numbers in this article because that’s how people are actually driving their cars and that is what’s comparable to the RS’s rivals. (FWD mode loss seems to be around 15%, so I’ll use roughly 20-25% to approximate AWHP)

Stock: 350bhp (~260-270awhp)

With 350hp on tap, the Focus RS is really where the STI should be by now in stock form. The RS seems to have no problem walking any STI that still has its stock downpipe, stock or tuned.

Tune w/ Stock Parts: 380-390bhp (~290-300awhp)

A tune alone will get you most of the peak gains available on the stock turbo, as well as a huge increase in power and torque in the low and mid rev range. It will transform the way the RS feels to drive, especially on public roads.

So why do any physical mods?

Making the power is one thing, but making it smoothly, consistently, and safely is another. If you want the ultimate Focus RS experience, some tangible upgrades are needed.

Bolt-On Mods w/ Tune: 380-400hp (290-310awhp)

By bolt-on mods, I mean an intake, intercooler, boost recirculation valve, and exhaust.

An intake seems to open up some restriction and add a couple more ponies. A larger intercooler keeps intake temperatures down, and allows the ECU to essentially run full boost all the time on the street. An improved recirculation valve stands up to higher boost temperatures better than the weak factory valve, allowing for safer, more consistent power. The stock exhaust is already pretty good, but an aftermarket exhaust will free up any restriction, while also making the car sound better than Ford is allowed to from the factory. As for a downpipe, it adds to the sound, but doesn’t do much for the performance while the stock turbo is still the limiting factor.

Now you’re maxing the stock turbo, and most RS owners will stop here with the mods. At this point you’ve got around 40whp more than stock overall, but with a power curve that has been totally transformed. Horsepower gains in the mid range are as much as 80whp over stock, and the car will be much more responsive and eager to sprint than before.

Yea, the Focus RS isn’t quite the stock turbo star that the Evo X or the Golf R are, but it’s surely no slouch at all. With such a wide powerband, brutal performance is there whenever you want it. It’s a hell of a rally car experience for the road.


But what if you still want more?

Well, now you come to a predicament: You need a bigger turbo, and everything that goes with it for your desired power level. At this point, a stronger clutch will be pretty much mandatory as well. Also, the Focus RS’s drivetrain is pretty complex, and parts of it are supposedly only built to handle the equivalent of around 450 ft/lbs of torque from the engine. If that’s true, then any big turbo kit will be pushing the stock drivetrain quite hard.

We’re talking at least a few thousand dollars here, though a clearer picture will show itself over time, after many cars have been broken. (I’ll update this article as that happens). Really, though, it’s not much different than any other car when it comes to adding a larger turbo. Anyone who attempts it knows damn well they’re going to be writing a few fat checks, and most of the people who’d care would have stopped well before now.



Modding wise, the Focus RS fits right in the pack with the other rally cars. It’s not the bolt-on master, but it is very competitive. The 300awhp mark, with loads of torque and a fat powerband, is an ideal level for a street-driven rally rocket. If you’re really attacking back roads or canyons, you’ll have a hard time using all of the performance in most places. You’ll also be able to smoke most other affordable performance cars, and probably  be able to embarrass most casual Ferrari or Porsche owners out there, especially when there are corners involved.

The Focus RS seems to want to be a rally car, through and through. If you want big horsepower, I say buy something else. If you want the rally experience in your life, I say buy an RS, do the basic mods and tuning, and enjoy trying to not land yourself in jail.

-Nick Walker


One thought on “Ford Focus RS Power Modifications and Tuning”

  1. I have stage one sti 295whp and 307tqw with forged pistons.. paid 1.8k$ for that. You still will choose RS? I mean its new car with new engine technique we dont know its problems yet .. while STI known with weak pistons which is 500$ to get them froged and u can go easily to 400whp safe.


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