MOTOCROSS ACTION PRODUCT TEST: DR.D KAWASAKI KX450F EXHAUST SYSTEM

WHAT IS IT? An easy horsepower modification for the Kawasaki KX450F.

WHAT’S IT COST? $619.99.

CONTACT? www.dubachracing.com or (877) 382-2241.

WHAT STANDS OUT? Here’s a list of things that stand out with the 2010 DR.D KX450F exhaust.

(1) Development. The KX450F received engine mods for 2010 that made a notable difference in power output. So, DR.D went back to work on developing a pipe to address the specific needs of the new bike. They lengthened the head pipe compared to the 2009 version and changed the bend. The result was a smoother bottom-end and an increase in midrange power. These are good mods, because in stock trim the KX450F’s bottom-end power is brutish and needs to be mellowed out a tad for mortal men.

(2) Performance. In a world that is dominated by dyno testing results, DR.D’s modus operandi is not to chase big peak horsepower numbers, but instead to focus on the usability of the power on the track. Doug Dubach knows that going fast in motocross is more about what the rider can do with the power than how much power there is. It’s no secret that the stock KX450F powerband is awesome, but from idle to the midrange it is an arm stretcher. DR.D’s KX450F cuts down on the unintended wheelies, frantic wheelspin and hang-on-and-pray moments in favor of a better modulated power delivery. It is easy to ride in tight turns, rutted corners and slippery terrain, because it meters the power off idle to be usable. It does make better power than the stocker from the middle on up.

(3) Preferences. Some MXA test riders preferred the abrupt hit of the stock pipe (probably because it made them punch-drunk). It is easy to understand their infatuation with the stock KX450F powerband: It hits hard, pulls like a team of oxen, and is virtually untouchable (if you are strong enough to hold on for a complete moto).

(4) Simplicity. The DR.D pipe should have a label that says: “This product contains no springs, clamps rubber grommets or trans fat.” It’s easy to install, and there aren’t many little parts to lose. The muffler is held together with bolts at the base to enable repacking. The muffler comes with a spark arrestor, just in case you want to hit some trails.

(5) Upgrades. DR.D also makes titanium/titanium ($869.99) and titanium/carbon fiber ($919.95) systems. These systems are all tuned for the same performance as our $619.99 stainless/aluminum system. They subtract a few ounces from both your bike and your wallet.

WHAT’S THE SQUAWK? Testers who had grown to love the hard-hitting stock powerband were less than enthralled with the mellow DR.D system. Even though the DR.D system is a little more powerful everywhere, its less aggressive delivery can feel slower at first.

If we were rating the DR.D KX450F exhaust on how much power it makes on the dyno, we’d give it three stars. But, until they take dynos to the starting line, we rate pipes on how much faster they are in the dirt. The DR.D KX450F exhaust makes the KX450F a lot easier to ride fast.