AMS Performance

Pros
Mitsubishi's latest-generation EVO debuts as the much-anticipated addition to the dominant lineage of everyone's favorite purpose-built rally/street car hybrid. And unlike many new-generation offerings that fail to support high performance bars set by their predecessors (without naming names), the EVO gets better with age. Along with significant suspension and driveline improvements, the EVO X brings an entirely new powerplant; the 2.0L, inline-four 4B11, which as we'll show, is able to make huge power from small monetary investments.

Cons
The 4B11 is an entirely new engine for the EVO X. As such, designing and building performance parts had to begin from scratch; previous generations of EVO parts aren't easily adapted to the X, and there are no other 4B11 Mitsu cars in production on our streets. And while it seems that the new powerplant will be able to produce the same big-power numbers that its daddy, the 4G63 could, there have been no all-out builds of the 4B11 thus far; tuners must tread lightly in these first few months.

Notes
Despite what this month's highly modded cover car might suggest, the EVO X is still a very new platform-at least, to those of us in the states. The car's early release in its homeland has given Japanese enthusiasts an impressive head start in aftermarket part development, but Americans haven't been so lucky. Japanese manufacturers are slow to export their parts to our shores, and although most major domestic parts manufacturers have power adders for the EVO X well in the works, currently only AMS has parts ready for distribution. and the unit's solid construction dispelled any qualms we might have previouIn this installment of Power Pages, we test the three components comprising AMS's Stage 1 upgrade package for the EVO X-to catch a glimpse of its tuning potential.

Pros
Top-end power increased dramatically, installation and operation are a cinch, and the unit's solid construction dispelled any qualms we might have previously had toward manual boost controllers (MBC). Most impressive was that power gains were made without actually raising boost. More on that below...

Cons
Fueled by boost-spike horror stories, some tuners might be leery of MBCs, but the truth is that most MBC failures occur from knock-off eBay units and/or people improperly adjusting boost. AMS did their homework when searching for an MBC to employ with their Stage 1 kit, and selected the most reliable unit they could find. Currently, no tuning solutions are available for the X yet, so it's probably not a good idea to raise boost too much-23 psi should be your limit, we're told.

Parts
Boost controller unit, vacuum lines, zip ties, bracket, caps, and tee.

Tools
Pliers, WD-40, included zip ties

Installation Time
30 minutes

Notes
In stock trim, our EVO X's boost pressure would rise to about 21 psi before falling steadily to 14 or 15 psi by redline; this happened for two reasons: The limiting size of the 4B11's turbo, and the EVO X's engine management system reducing boost pressure as rpm increases, keeping power production below a certain threshold. Installing the MBC effectively severs the EVO ECU's ability to control boost production, allowing boost to hold more steadily approaching redline. Boost was still limited to the stock 21 psi setting for all stages of testing, but because pressure couldn't be tapered off approaching redline, power increased. The only downside is a bit of instability in the mid- and low-range rpm, and that installing the MBC may prompt a check-engine light at partial throttle-but we're told some quick ECU tuning will cure both these woes...once it becomes available.

Pros
Not only did the intake make power across the board, it seemed to level out our fluctuating powerband considerably. What's more, the AMS unit included silicone tubing to accommodate the stock bypass valve. The overall solid construction, easy installation, and sneaky larger-diameter MAFS housing add to the intake's appeal. Sneaky? Read the Notes section below.