Every time I get behind the wheel of a BMW equipped with a 3.0L turbocharged engine I spend a good amount of my time contemplating why BMW would handicap such a great car. Why restrict an engine with so much obvious potential? It’s not for emissions or fuel economyseems it has more to do with cannibalizing M3 sales. We decided to see if a few simple mods can close the power gap between the 335i and M3.

Vehicle Data

Engine: 3.0-liter I6, dohc, 24-valve
Transmission: Six-speed manual
Drivetrain: rear-wheel drive
Mileage: 36,458

Dyno Data
Dyno Type: Mustang MD-AWD-500 in two-wheel-drive mode
Temperature: 76F -82F
Transmission test gear: Fourth

Baseline
Temperature: 76F
Humidity: 24%
Peak power: 265 hp @ 6100 rpm
Peak torque: 268 lb-ft @ 3800 rpm

Test Notes
The baseline and all subsequent testing were performed on the same day, utilizing the same tank of 91-octane fuel.

All horsepower and torque numbers are quoted at the wheels. It is also important to keep in mind that the properly calibrated Mustang dyno produces more accurate real-world horsepower and torque numbers. While these numbers might seem low when compared to figures gathered from a Dynojet, what is important is the differences between each dyno run. These differences are what we use to verify the validity of the manufacturer’s horsepower and torque claims.

GIAC Stage 1 DME Software Upgrade 91 Octane / AE Performance Exhaust

Test 1

Performance
Peak power: 318 hp @ 6100 rpm
Peak torque: 336 lb-ft @ 4150 rpm
Max power gain: 53 hp @ 5800 rpm
Max torque gain: 75 lb-ft @ 4200 rpm

Temperature: 82F

Humidity: 29%

GIAC Stage 1 DME Software Upgrade 91 Octane

Install process: OBD Port Flash
Installation time: 45 minutes
MSRP: $800

Pros

  • OBD port flashing leaves the ECU and harness completely unmolested
  • Increased throttle response and smoother power transitions
  • Increase rev limiter to 7200 rpm
  • Speed limiter is removed in the DME software without affecting ABS and DSC functions
  • DME receives accurate data from the engine sensors, giving the ability to be more proactive instead of reactive, allowing DME to deliver the proper amount of fuel, cam and engine timing based on real-world conditions
  • 100% reversible

Cons

  • None

AE Performance Full Exhaust

Parts: Front pipe, RT and LT muffler pipe, RT and LT muffler assembly with 89mm dual hand-rolled tips, gaskets, stainless steel hardware
Tools: T50 torx bit, 15mm, 18 mm and 5/16-inch socket, extension, ratchet, WD-40
MSRP: $1,795
Installation time: 60 minutes

Pros

  • T304 stainless steel construction
  • Laser-cut flanges makes the system a direct bolt-on
  • 24 pound weight savings over the stock system
  • No cutting of the stock exhaust system
  • Use of flanges and gaskets ensures a leak-free system
  • Removes secondary catalytic convertors
  • No check engine light

Cons

  • Not street legal

GIAC Stage 1 DME Race Software Upgrade / VP100 Race Fuel

Test 2
Peak power: 332 hp @ 6000 rpm
Peak torque: 365 lb-ft @ 4350 rpm
Max power gain: 21 hp @ 5500 rpm
Max torque gain: 36 lb-ft @ 4500 rpm

Temperature: 82˚F
Humidity: 29%

Temperature: 82F
Humidity: 29%

GIAC Flashloader HandHeld Price:
Flashloader Handheld $150
Race Mode Performance Program $200
Installation time: If purchased separately the upgrade takes approximately 1 hour

Pros

  • With a simple push of the read button the LED illuminates the current program setting thus reducing confusion
  • Allows the driver to get the full advantage of the 100 octane fuel
  • Valet option helps you keep the power all to yourself by putting the vehicle in a significantly detuned state
  • Kill option is designed to make the car inoperable
  • Stock option makes trips to the dealer less stressful

Cons

  • All the bells and whistles add up

VP100 Street Performance Fuel
Price: $7.99 per gallon (est.)

Pros

  • Prevents excess timing retard that can reduce horsepower
  • Helps maintain power in extreme temperatures
  • CARB approved street legal 100 octane designed for street and track use
  • Contains no metal compounds that can destroy catalytic converters or oxygen sensors

Cons

  • Excessive use can take a big chunk out of your wallet

Conclusion

When I first drove the stock 2007 BMW 335i, I will admit, it’s an impressive machine but with a touch of ADHD. It had oodles of power but no direction. At the end of the drive, it left me with a strange and unsettling sensation of being fast without feeling fast.

When a car isn’t feeling right, one immediately takes it for a tune-up. And it seems that modifying the car is like administering a dose of Ritalin. After the chip and exhaust, the first thing I noticed is that the GIAC Stage 1 has somehow unconfused the 335i. It no longer seems to struggle and it knew exactly what to do which resulted in better than factory power delivery. As soon as I got behind the wheel, the difference was immediate. From tip in to full throttle through every gear the power delivery was smooth and lag-free. The vehicle’s e-gas pedal was more precise and linear showing no hint of being over exaggerated (i.e. 1/4 throttle gives you full boost and full throttle give you nothing), giving the driver full control of the vehicle powerband. The optional GIAC Race program adds an extra dimension to the 335i powerband and the 100 octane fuel helps fight detonation, keeping the power consistent whether you are blasting through the canyons, spending the day at the track or just out to humiliate others around town. To top it off, the BMW even sounded better with the AE Performance exhaust adding a good balanced tone throughout the entire rpm range.

Upgrade Summary

GIAC Stage 1 Software $800
GIAC Stage 1 Race Mode $200
GIAC Hand-Held $150
AE Performance Exhaust $1,795
MSRP total $2,945

SOURCE
GIAC USA
1350 Reynolds Ave, Suite 106
Irvine
CA  92614
949-724-0014
www.giacusa.com
AE Performance
714-241-0298
www.aeperformance.com
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