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Seoulfulracing ECU Reflash - Proving Grounds

Helping the Hyundai Genesis coupe reach its true power potential

Aug 1, 2013

Test Mule: 2013 Hyundai Genesis 2.0T and 2012 3.8L V6

2.0L, direct-injection, turbocharged-four and 3.8L naturally aspirated V6

Hyundai genesis seoulfulracing ECU reflash dynomometer Photo 2/9   |   Seoulfulracing ECU Reflash - Proving Grounds

Relevant Mods
Intake and full exhaust

Key Features

  • Improves not only horsepower and torque but adds sportier overall driveability
  • Rev limiter can be raised and speed limiter removed
  • ECU can always be reflashed back to stock
  • Retains factory driveability and safety features
  • Mail-in reflash turn-around in one to four days


On paper, the Genesis coupe seems like a sure winner with great RWD performance at a bargain price. In reality, the Gen coupe hasn’t been the home run hit we’d hoped for. However, that doesn’t mean the potential to modify this platform isn’t there. With the right modifications, this already well-equipped chassis can rival much more expensive cars in the performance department.

Hyundai genesis seoulfulracing ECU reflash jay kim tuning Photo 3/9   |   Here’s a rare sneak peek at SFR’s Jay Kim reprogramming a mail-in tune ECU.

The best modification for the vehicles also happens to be the simplest and most cost effective. An ECU reflash can net significant horsepower and torque gains, but that’s not all it does. Tuning the right parameters can improve throttle response, raise the rev limiter, and even enhance fuel economy while still maintaining the OEM driveability and functionality of the car.

There are, however, risks, the main one being a bad tune resulting in poor engine performance or even worse, a blown motor. That’s why finding a reputable and proven ECU tuner is key. In the Hyundai Gen coupe world, Seoulfulracing has earned its reputation by providing rock-solid reflashes and tunes to more than 400 satisfied customers.

Offering mail-in reflashes and custom dyno tunes, SFR can increase power output on ’10-’13 2.0T models by 30-50 whp and 50-70 wtq. The ’10-’12 V6 models can benefit from a tune as well, gaining 10-plus wheel horsepower and 20-plus wheel torque. Figures vary depending on supporting modifications, but as with any vehicle, a good intake and full exhaust system can greatly enhance an ECU tune.

Hyundai genesis seoulfulracing ECU reflash 2013 gains Photo 6/9   |   The new ’13 2.0T Gen coupes have a ton of potential;

Since SFR uses a nonintrusive method of modifying the ECU’s parameters, the factory warranty is still retained, and even dealership ECU updates can be applied with no ill effects. It’s safe to say that the car runs and operates just like stock but with more power and a crisper throttle response. With a price tag of $550 for the 2.0T and $600 for the V6, the SFR mail-in ECU reflash or on-site dyno tune (you can bring your car to SFR for a custom dyno tune) is undoubtedly the best bang-for-your-buck performance mod.


Hyundai genesis seoulfulracing ECU reflash 2013 engine bay Photo 5/9   |   with the right tuning and supporting mods, gains of almost 50 whp and 70 wtq can be had.

We wrung out our 2.0T (’13) and V6 (’10) Gen coupe test subjects on a DynoJet dyno before each received its respective reflash. A free-flowing intake, upgraded intercooler and piping, and full turbo-back exhaust were the aftermarket mods on the 2.0T, while the V6 had a short-ram intake and after-cat exhaust fitted to it.

Hyundai genesis seoulfulracing ECU reflash 2013 gains Photo 6/9   |   The new ’13 2.0T Gen coupes have a ton of potential;

The 2.0T spun the rollers to the tune of 239 whp and 231 wtq, while the V6 produced a very healthy 287 whp and 246 wtq. Jay Kim, owner and tuner of Seoulfulracing, loaded his reflash into each machine’s ECU, and after he tweaked timing and air/fuel ratios as well as some other parameters, the results were in.

Our turbo four-banger now produced 288 whp and 302 wtq, which means it gained a whopping 49 whp and an unbelievable 71 wtq, all while on the factory turbo and fuel system.

It’s usually hard to make solid gains from naturally aspirated engines, but Hyundai left a lot on the table with its stock tune. SFR managed to squeeze the V6 to 302 whp and 272 wtq. It’s great to see solid gains of 15 whp and 26 wtq almost across the entire rpm range.

Hyundai genesis seoulfulracing ECU reflash open engine bay Photo 7/9   |   The 3.8L V6 engine is no slouch, making 288 whp and 246 wtq. However, add a tune to it, and 300 whp is realized with a bump of 26 wtq.

Both vehicles also received remapped throttle input, greatly enhancing the driveability of the cars. The rev limiter was also raised to 7,200 rpm, netting the engines more time in their optimal powerbands.

As you can imagine, the SFR reflash changes the character of the Gen coupes in more ways than one. What it doesn’t do is affect the daily driveability of these cars, and that, to us, is equally important. The Gen coupes maintain their civil, stocklike demeanor in light-throttle cruising conditions, but lay into the gas pedal and it’s a whole new beast—one that spins the tires with ease and pushes you back in the seat.

Hyundai genesis seoulfulracing ECU reflash 2 0 turbo Photo 8/9   |  
Gen Coupe 2.0T

Gen Coupe 2.0T

Gains Made
+49.16 whp
+72.15 lb-ft tq

Before 238.99 whp and 230.84 lb-ft
After 288.15 whp and 302.99 lb-ft

Hyundai genesis seoulfulracing ECU reflash 3 6 v6 engine Photo 9/9   |  
Gen Coupe 3.8L V6

Gen Coupe 3.8L V6

Gains Made
+14.21 whp
+ 26.26 lb-ft tq

Before 287.89 whp and 246.03 lb-ft
After 302.10 whp and 272.29 lb-ft


Seoulful Racing



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