Hondata's ECU Reflash for the 2006 Honda Civic Si - Making Honda's Best Si Better

Finding dramatic improvements from small, sometimes intangible or even free modifications is often disconcerting to us-like finding huge power gains from just a little bit of ECU tweaking on a fairly stock vehicle. Don't get us wrong. We welcome the improvements, it just bothers us a bit. It's enough to make us wonder: If they're that easy and cheap, why weren't they implemented in the first place? We often try to figure out why the manufacturer might not have addressed a particular issue on the assembly line or on the drawing board. It often boils down to ugly things like emissions concerns, cost-cutting measures and plain old corporate practicality.

When you think of the '06 Civic Si, it's unlikely you'll conjure up images of accountants brawling it out with engineers in an effort to produce a vehicle economically on par with one of the company's lesser competitors at the expense of its technical traits. No, we have no qualms when it comes to Honda's commitment to quality, performance and attention to detail. We're not the only ones saying it either. This is arguably the best Si we've been handed in over six years. It also looks like there was a brawl, at least the engineers won. But when we picked up 30 hp in the Si's midrange all from just a simple ECU reflash, we were nothing short of confused. Impressed, but still confused. Hondas typically just don't see gains like this when it comes to ECU tuning. At least not ones like our test Si, with just simple bolt-ons. Either Honda skimped somewhere or Hondata's done something incredible.

We've learned a couple of things about Honda's latest K-series since we first got our hands on the Si. Although quite similar to the RSX Type S' K20A2 mill, the K20Z3 differs in more than a few ways. For one, Honda outfitted the Si engine with a chain-driven balancer in an effort to smooth out engine operation. We can tell from our experiences with the Prelude H22A engine that this added civility comes at a cost-a few horsepower to be exact. So Honda, in what seemingly appears to be an attempt at retrieving that lost power, outfitted the Si with one of the most impressive intake manifolds we've tested on the K-series engine yet. Most importantly, we've learned that the Si's ECU architecture is quite different from its K brethren. Its drive-by-wire throttle, which is controlled completely through the ECU, is the culprit. Now the ECU directly controls the vehicle's idle, cruise control system and throttle. Say good-bye to Honda's long-time TPS (throttle position sensor) and IACV (idle air control valve). As such, Hondata's popular Windows-tunable K-Pro doesn't work here. So Hondata did the next best thing: It developed a reflash compatible with the Si's K20Z3 engine paired with either of the latest RRB computers.