The E46 M3 was blessed with an extremely stout powertrain from the factory. The 3.2-liter straight-six stirs up 333hp and 262 lb-ft which, paired to a great chassis, made it a benchmark performer.

With a solid-lifter cylinder head and 8000rpm limiter, it's meant to rev hard and is happiest past 5000rpm. And while the stock power levels are appropriate, the E46 weighed upwards of 3400 lb and the chassis can definitely cope with more power, so we set out to extract as much power as possible while staying within the limits of the factory hardware.

We teamed up with european auto source (EAS) in Anaheim, CA for every step of the build. Utilizing their in-house DynoJet dynamometer, wide array of parts and top-level mechanics, we were in good hands.

Before doing anything, we wanted to set a baseline for our stock M3 with 68000 miles on the clock. Our car had been maintained religiously throughout its life, and the numbers proved it. The car made an above-average 294hp and 245 lb-ft at the wheels - not bad for ten year-old car!

Exhaust

Unfortunately, the US-spec M3 was fitted with restrictive headers and catalytic converters. So while the Europe-only CSL had free-flowing parts, they're hard to come by. And with the installation being as tricky as it is, it made more sense to upgrade to something altogether better: Macht Schnell.

Using laser-cut 3/8" flanges, these headers create a perfect seal to the head and are guaranteed not to warp. They were inspired by the CSL headers and are mandrel-bent to ensure maximum flow. The precision welding is seamless, along with OEM oxygen and EGR bung locations, plus an additional bung for our Stack wideband O2 gauge. Better yet, they're gorgeous - although hidden once installed - and cloaked in a matte black ceramic thermal coating inside and out to improve thermal efficiency. This helps keep under-hood temps down and maintain exhaust velocity.

We decided to finish off the system with Borla's newest exhaust for the E46; the "ATAK" cat-back. Sure, we wanted to maximize our gains, but the 3.2L S54 motor is notoriously raspy. It's a sound we don't mind enhancing, but it had to be done with class. Often, these M3s can sound tinny or drone but Borla's new system is easily among the best we've heard. Even the guys at EAS were surprised and agreed it was a quality piece.

Using a three-section solution, Borla nailed it with the "X" pipe, resonator and rear muffler creating an aggressive, exotic noise that can be easily tamed with throttle control.

Of course, the car's inevitably louder with the cat-less headers, but we love it. And without being re-tuned, the M3 put down 310whp and 249 lb-ft with all the exhaust parts in place.

While the numbers were nice, the on-road manners were drastically improved. Low- and mid-range response was immediate, and the motor came alive. For a reliable daily driver, these simple modifications are perhaps all you need if you're on a tight budget, transforming the car's attitude. However, the headers won't be legal in most states. That said, we couldn't stop there. We wanted more.

ESS VT1-445

For the next step, we weighed our options, looking at both turbo and supercharger kits. In the end, we opted for a centrifugal blower because it makes boost by engine speed, meaning that as the motor revs higher, the supercharger spins faster and makes more boost.

For the S54 motor, this is a great option because it retains the linear nature of the factory powerband but moves it up the graph. The attitude and personality of the motor isn't changed, but enhanced, and that was exactly what we wanted.

We then chose the ESS Tuning kit because it's been extensively tried and tested. From parts quality to servicing and ECU tuning, the ESS kits are virtually unmatched and unrivaled. Nicest of all, the kits are upgradable. The same supercharger is used from the mildest to wildest set-ups, so only the ancillary parts need to be swapped out during the upgrade process.

ESS uses the Vortech V3Si supercharger in its E46 M3 systems, capable of up to 775hp and, unless you plan to fully build your bottom end, you'll never need more than this unit can provide.

We started with the basic kit, the VT1-445. With installation taking roughly six hours, we wouldn't recommend it for the weekend-wrencher, although it's completely possible if you have the experience and tools. The straight-six is squeezed into the engine bay as it is in stock form, so fitting these large parts is an exercise in finesse, and when messing with drive belts there's very little room for error. One tooth off the crank pulley and you can kiss your motor goodbye.

We had EAS to complete the conversion, and it's one they'd done hundreds of times. The VT1 kit is non-intercooled, reaching a maximum of 5psi. A new cast aluminum intake manifold with integrated bypass valve replaces the large factory part, while bigger Bosch Motorsport fuel injectors are added to keep the gas flowing.

The VT1-445 kit is rated at 445hp (which works out to about 375hp at the wheels), but our healthy M3 put down 414whp (487hp) and 295 lb-ft using weak 91-octane fuel on the EAS dyno.

The ESS software tune was flawless and factory-smooth, without any glitches. With just 5psi, the car felt impressively eager, and our more-than-advertised power was welcomed.

The kit provided great power for the money but with California summers and the possibility of some track use, we wanted the extra cooling from a front-mount intercooler and were soon yearning for more power!

ESS VT2-525

As it happens, ESS Tuning had developed a new upgrade for the E46 M3 and used our car to test its VT2-525 conversion. The kit was designed to maximize output on 91-octane gas, pushing as far as they could before extra boost would require better fuel. And since Project E46 sees daily road use, we currently don't plan to push beyond this stage.

Swapping the supercharger pulley to increase the boost, and adding bigger injectors, along with a bar-and-plate intercooler is all it took to upgrade from the VT1 kit. Though not nearly as intensive as the initial install, this upgrade involves two pulley swaps along with removing and trimming the front bumper to fit and align the intercooler.

The intercooler and piping were finished in a stealthy black powdercoat to match the intake manifold and compressor housing, keeping things under the radar.

Boost pressure was increased to 9psi and the ECU was recalibrated with new ESS software, along with a raised rev limit to 8400rpm. We don't recommend revving your M3 this high, but the power continued to climb past 8000rpm on our car and we enjoy the sound! Again, our Bavarian beauty saw a substantial power increase on the dyno, beyond what even ESS Tuning expected. This was probably thanks to the Macht Schnell headers, and having a sound base vehicle.

So after spinning the dyno we recorded a gain of 58hp, giving us 472whp. By factoring in an approximate 15% drivetrain loss, this put our M3 at about 555hp at the flywheel, which was 30hp more than ESS expected.

Overall, we gained 178whp over our original stock runs, increasing factory output by a whopping 60.5%. So yes, you could say we are satisfied with the results!

The car is now ferociously rapid under acceleration. Gears fly by and 140mph comes up very quickly. First gear is still usable with our 275-series Falken RT-615K tires, although the gear ends almost instantly in wheelspin. Second gear also spins, depending on the road surface, but if there's any steering angle you can bet the rear-end will slide out.

Actually, that's true of full throttle into third gear as well, making it an entertaining ride if you're looking for fun.

The ESS Tuning VT2-525 kit is perfect if you're looking for an astonishingly fast yet remarkably reliable road car that will lap most vehicles costing three times its price. We're always hungry for power, but our appetite has certainly subsided.

SupplierPartPriceContact
ESS TuningVT1-445 supercharger kit$5495esstuning.com
ESS TuningVT2-525 supercharger kit$7795esstuning.com
Macht Schnellmotorsport performance headers $1395machtschnell.com
Borla ExhaustATAK cat-back exhaust$2472borla.com

Next Month We'll take a look at the upgrades that brought the M3's chassis up to par with the supercharged horsepower

By Alex Bernstein
Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!