Bringing review over from now-dead site.
Installation
The individual components are well packaged and everything is of very high quality.
The supplied installation manual is very comprehensive and has detailed step-by-step instructions with accompanying pictures. A negative is that some of the pictures are not as well lit as they should be so a few steps can be confusing. The manual also combines steps from several different kits and generations (VT1-475 & VT2-525/550/575, generation 2 and 3), which can cause unnecessary confusion in places. Overall, however, the instructions are pretty solid.
Unless you are familiar with working on M3s, the 6-8 hours installation time mentioned on the main product page might be optimistic. I have a fair amount of experience working on other cars but not so much on my M3 (oddly, it has been as reliable as a Honda during my 8 year/40k mile ownership) so a few things were time consuming. In particular, I had a bear of a time installing the injectors. The fuel rails to injector clips and the electrical connector clips can be a pain to work with until you get the hang of them. Properly aligning the fuel rail and injector components before tightening is also tricky. I also damaged an o-ring on one of the ESS injectors during the installation and had to order a new one. (The injectors are custom Siemens ones developed for ESS but use the same o-rings as the stock injectors.) I suspect I spent close to 6 hours alone dealing with injector issues.
Several stock parts also need to be modified during the installation, a process that was also time consuming. For example, the bumper, undertray and left-hand-side brake cooling duct need to be trimmed during the installation The manual does not include trimming templates - so you are on your own. The stock power steering reservoir bracket also need to to be modified to work in the reservoir's new relocated position. I spent 2-3 hours trimming these parts, with the bumper trimming taking the most time.
The only thing I really disliked about the kit was the (apparent) need to cut the MAF/IAT connector from the factory harness before connecting the new IAT connector that came with the kit. Fortunately, I discovered that I could t-tap into the wires on the harness to attach this new connector. Cutting factory harnesses is almost never a good idea (particularly when the connector cannot be ordered by itself) and I am surprised that ESS did not go with the much simpler (and reversible) t-tap approach here.
Another challenge was bending one of the high pressure power steering hose to allow fitment of the piping from the intercooler to the intake manifold. The terse instructions and poorly lit picture for this step did not help. I got the piping to fit but some components are rubbing together, causing a squeaking noise at low speeds. I am going to have to redo this step and may have to remove the power steering line from the car to properly bend it.
Once installed, the hardware looks stock. My only regret is not checking the option to powdercoat the supercharger black, which would have produced an even more stock look.
Initial Startup
After receiving the tune from ESS I uploaded it to the car via the supplied E-Flash cable and software. The car started up immediately - but I quickly turned it off after hearing a terrible racket from the engine bay.
The source of the noise was the supercharger!
It sounded like it was filled with loose bolts and metal shavings. I initially thought that all the oil had leaked out but when I checked the level it was correct. I then searched online and discovered that this type of noise was normal for this type of supercharger at idle speeds. Fortunately, when the hood is closed the noise is barely audible and is completely inaudible from inside the car.
Once that 'problem' was resolved I started the car again. Again, the car started up immediately, this time going through the stock idle stages, and eventually reached a rock solid idle. The RPMs quickly and smoothly returned to idle after throttle blips.
So far, so good.
On the Road
There is a break-in period (vaguely specified in the manual as "drive the car soft for 200 miles") so I kept the RPMs under 4k RPM for that amount of miles. Under 4k RPM the car essentially drives like a stock car. In fact, the presence of the supercharger is not really noticeable. Some people report a whining or a whistling noise, but these are not audible to me.
As can be seen from this ESS dyno chart, up to 3k RPM the increase in horsepower and torque is minuscule; even at 4k RPM the increase is not substantial.
Above 4k RPM the car comes alive in the same way as the stock car, except torque does not drop after 5k RPM and horsepower climbs in an astonishingly linear fashion to 8k RPM. On the road this means that the car is utterly underwhelming under 4k RPM and almost ridiculously powerful after that.
As with the stock car, the car has to be kept on the boil to feel fast. Unlike the stock car, at high RPM power levels the car is lunatic fast rather than just very fast. If you don't regularly hit high RPMs, this kit might be a waste of time. (Which, arguably, could be said of the stock E46 M3 too!)
Verdict
I can see the argument for keeping the E46 M3 naturally aspirated since the engine is a marvel. However, this kit does not really change the fundamental nature of the car. It's still the same highly strung, quick-revving, noisy beast as before - except power is now at supercar levels at high revs. Power delivery is incredible. Drivability is stock-like, with none of the dodgy idle and dead spot issues that can bedevil aftermarket tunes.
While the kit is not cheap at $7k or so, on a dollar-per-horsepower basis it is impressive. The kit can also be easily removed and can generally be sold for $4-$5k. And, unlike many mods, it is possible to recoup a reasonable amount of the initial outlay when selling with the car - if recent Bring a Trailer auctions of supercharged M3s are indicative.
Installation
The individual components are well packaged and everything is of very high quality.
The supplied installation manual is very comprehensive and has detailed step-by-step instructions with accompanying pictures. A negative is that some of the pictures are not as well lit as they should be so a few steps can be confusing. The manual also combines steps from several different kits and generations (VT1-475 & VT2-525/550/575, generation 2 and 3), which can cause unnecessary confusion in places. Overall, however, the instructions are pretty solid.
Unless you are familiar with working on M3s, the 6-8 hours installation time mentioned on the main product page might be optimistic. I have a fair amount of experience working on other cars but not so much on my M3 (oddly, it has been as reliable as a Honda during my 8 year/40k mile ownership) so a few things were time consuming. In particular, I had a bear of a time installing the injectors. The fuel rails to injector clips and the electrical connector clips can be a pain to work with until you get the hang of them. Properly aligning the fuel rail and injector components before tightening is also tricky. I also damaged an o-ring on one of the ESS injectors during the installation and had to order a new one. (The injectors are custom Siemens ones developed for ESS but use the same o-rings as the stock injectors.) I suspect I spent close to 6 hours alone dealing with injector issues.
Several stock parts also need to be modified during the installation, a process that was also time consuming. For example, the bumper, undertray and left-hand-side brake cooling duct need to be trimmed during the installation The manual does not include trimming templates - so you are on your own. The stock power steering reservoir bracket also need to to be modified to work in the reservoir's new relocated position. I spent 2-3 hours trimming these parts, with the bumper trimming taking the most time.
The only thing I really disliked about the kit was the (apparent) need to cut the MAF/IAT connector from the factory harness before connecting the new IAT connector that came with the kit. Fortunately, I discovered that I could t-tap into the wires on the harness to attach this new connector. Cutting factory harnesses is almost never a good idea (particularly when the connector cannot be ordered by itself) and I am surprised that ESS did not go with the much simpler (and reversible) t-tap approach here.
Another challenge was bending one of the high pressure power steering hose to allow fitment of the piping from the intercooler to the intake manifold. The terse instructions and poorly lit picture for this step did not help. I got the piping to fit but some components are rubbing together, causing a squeaking noise at low speeds. I am going to have to redo this step and may have to remove the power steering line from the car to properly bend it.
Once installed, the hardware looks stock. My only regret is not checking the option to powdercoat the supercharger black, which would have produced an even more stock look.
Initial Startup
After receiving the tune from ESS I uploaded it to the car via the supplied E-Flash cable and software. The car started up immediately - but I quickly turned it off after hearing a terrible racket from the engine bay.
The source of the noise was the supercharger!
It sounded like it was filled with loose bolts and metal shavings. I initially thought that all the oil had leaked out but when I checked the level it was correct. I then searched online and discovered that this type of noise was normal for this type of supercharger at idle speeds. Fortunately, when the hood is closed the noise is barely audible and is completely inaudible from inside the car.
Once that 'problem' was resolved I started the car again. Again, the car started up immediately, this time going through the stock idle stages, and eventually reached a rock solid idle. The RPMs quickly and smoothly returned to idle after throttle blips.
So far, so good.
On the Road
There is a break-in period (vaguely specified in the manual as "drive the car soft for 200 miles") so I kept the RPMs under 4k RPM for that amount of miles. Under 4k RPM the car essentially drives like a stock car. In fact, the presence of the supercharger is not really noticeable. Some people report a whining or a whistling noise, but these are not audible to me.
As can be seen from this ESS dyno chart, up to 3k RPM the increase in horsepower and torque is minuscule; even at 4k RPM the increase is not substantial.
Above 4k RPM the car comes alive in the same way as the stock car, except torque does not drop after 5k RPM and horsepower climbs in an astonishingly linear fashion to 8k RPM. On the road this means that the car is utterly underwhelming under 4k RPM and almost ridiculously powerful after that.
As with the stock car, the car has to be kept on the boil to feel fast. Unlike the stock car, at high RPM power levels the car is lunatic fast rather than just very fast. If you don't regularly hit high RPMs, this kit might be a waste of time. (Which, arguably, could be said of the stock E46 M3 too!)
Verdict
I can see the argument for keeping the E46 M3 naturally aspirated since the engine is a marvel. However, this kit does not really change the fundamental nature of the car. It's still the same highly strung, quick-revving, noisy beast as before - except power is now at supercar levels at high revs. Power delivery is incredible. Drivability is stock-like, with none of the dodgy idle and dead spot issues that can bedevil aftermarket tunes.
While the kit is not cheap at $7k or so, on a dollar-per-horsepower basis it is impressive. The kit can also be easily removed and can generally be sold for $4-$5k. And, unlike many mods, it is possible to recoup a reasonable amount of the initial outlay when selling with the car - if recent Bring a Trailer auctions of supercharged M3s are indicative.
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