Conclusion
We feel this is the way the vehicle should have come from the factory. That said, the first thing you notice is that the GIAC Stage 1 has somehow "unconfused" the 335i. The difference is immediately apparent from behind the wheel. From tip-in to full throttle, the power delivery is smooth and lag-free. Unlike some tuned turbo cars where the accelerator positions are over exaggerated (i.e., quarter throttle gives you full boost while three-quarters gives you nothing) the 335i's power delivery based on pedal position is very balanced, giving full control of the powerband.

A perfect example of how the Stage 1 software lets the DME know what's really going is especially clear if you're drivingan automatic. With piggyback modules the automatic transmission would over time begin to shift harshly, inconsistently, and somehow seemed confused about what to do. This makes sense, considering that the transmission relies on load and speed data from the DME to operate. With GIAC software installed the automatic was transformed, more predictable, and gear-to-gear transitions were quick and smooth (no clunky shifts).

From a standstill, with the tranny in S mode and the accelerator inducing full throttle, I was amazed how quickly the car reacted and pulled all the way to redline. It behaved more like it had a V8 than a turbo six. A quick run through the canyon gave me another surprise: the vehicle's ability to sustain power whether I was on flat ground, powering out of a corner, or going up hills-again pulling all the way to redline.

We didn't expect power gains from the Borla exhaust, ultimately because it doesn't take care of the second set of catalytic converters, a major restriction in the factory exhaust. Borla does offer a set of race pipes that eliminates the secondaries (for off-road use only); we'll be testing these at a later date when GIAC's Stage 2 software becomes available. The exhaust did give a tasteful baritone resonance without becoming overly "boomy," which can be a frequent problem with automatic transmissions.

PARTS COST
GIAC STAGE 1 SOFTWARE  
  $800
BORLA CAT-BACK EXHAUST
  $1,301.99
MSRP TOTAL. $2,101.99

A quick note...
...for those concerned about their dealer uncovering software modification. This exact 335i has been to a couple different dealerships more than a half dozen times. As we noted earlier, it even had its fuel pump replaced. The dealers never once reprogrammed the DME or any other of the 18 systems that required updates.

Following the install, I stopped by a local BMW dealer to see a friend and why this vehicle had never been updated. He informed me that the updates take a long time to perform, they tie up the equipment, and they don't really get paid much to do it, so unless it's absolutely necessary, they don't bother.

While I was there I asked him to call out one of his greenest techs to see if he could tell whether the DME had been physically accessed. Within a minute he was able to point out a couple things that might indicate someone had tried to remove the cowling, and he was correct since the 335i did have a piggyback unit installed at one point. By then it had been removed, but traces from the installation and removal process were evident. Before I let him go I asked him if he routinely looked for this type of stuff. He replied: "I wouldn't look for it. I would only notice it if I happened to come across it during a repair or service." No matter what you choose to do with your own vehicle, keep in mind that if you play with the system, you must be prepared to deal with the consequences.

Having put a few thousand miles on various piggyback devices, I'm very familiar with them and I can honestly say that I've never had any issues. Then again, I never felt completely comfortable with the way they work. I think it's important when you tune a vehicle that every aspect of the software is recalibrated to accommodate the increases in power and torque, because power affects each system differently. Stay tuned for our Stage 2 testing as soon as the software becomes available.-AG

SOURCE
Borla
701 Arcturus Avenue
Oxnard
CA  93033
805-986-8600
http://www.borla.com
GIAC
1350 Reynolds Ave, Suite 106
Irvine
CA  92614
949-724-0014
www.giacusa.com
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