MXA PRODUCT TEST: DR.D 2008-2009 Yamaha YZ450F Exhaust System

WHAT IS IT? An exhaust system that will perk up the detuned 2008 and 2009 Yamaha YZ450F.

WHAT’S IT DO? If you own a 2008-’09 Yamaha YZ450F you know that Yamaha’s engineers seriously detuned the YZ-F. Why did they cork up the YZ450F powerband? Two reasons:

   (1) Yamaha wanted to make the 450cc four-stroke easier to ride for the mass majority of riders.

   (2) Yamaha wanted to reduce sound and test the worthiness of their unique waffle-cone mechanical muffler. The muffler uses cone-shaped diffusers to reduce the energy of the engine’s pulses. The results of Yamaha’s two-prong power/sound program are a one decibel reduction in sound, nine ounce weight savings and, unfortunately, a five-horsepower loss at 6000 rpm.

   It will come as no surprise that the MXA wrecking crew felt that Yamaha made a mistake. We applaud their sound reduction efforts, but believe that Yamaha could have achieved the same thing without costing the YZ450F most of its low-to-mid power. Luckily, it is easy to get back the power that Yamaha lost with an aftermarket exhaust system. That is where DR.D comes in. DR.D stands for Dubach Racing & Development and headed by Yamaha’s chief test rider Doug Dubach.

WHAT STANDS OUT? Here’s a list of things that stand out with the DR.D 2009 Yamaha YZ450F exhaust system.

    (1) Performance. Building a better exhaust system for the 2009 YZ450F is like shooting fish in a barrel. Virtually any straight-through muffler will eliminate the stocker’s corked-up feel. But, Doug Dubach didn’t stop there. As you would expect from the man who did the initial development work on all of Yamaha’s four-strokes, he knew better than anyone else what the YZ450F needed. Doug’s goal was not to make the YZ450F into a fire-breathing dragon, but to make it better everywhere. Starting with throttle response, through a strong midrange and a virtually seamless top end, the DR.D exhaust was amazing. It’s not just better than the stock YZ450F muffler, but better than we expected overall.

   (2) Material choices. DR.D pipes are available in four different material choices: Titanium pipe with carbon fiber muffler, titanium pipe with titanium muffler, stainless pipe with carbon fiber muffler and stainless pipe with aluminum muffler. All DR.D mufflers come with magnesium end caps. If you are asking for our advice, we recommend the stainless/aluminum system. It offers the same performance as the high-priced spreads, but at a price that is several hundred dollars less. If weight is an issue, go with the Ti/Ti system. The carbon fiber muffler is lighter, but MXA never recommends carbon fiber mufflers. They have such a short lifespan that they aren’t reliable enough for us to suggest that racers spend money on them.

   (3) Weight. DR.D’s Ti/Ti and Ti/carbon pipes are one pound, eight ounces lighter than the stock Yamaha YZ450F system. Their $330 less expensive stainless/aluminum system weighs the same as the stock exhaust.

   (4) Good stuff. Things we like about the DR.D design are that the perf core is welded to the mid-pipe (this makes it easier to repack), the head pipe flange is super sturdy (we have problems on some pipes with their flanges), the end cap is magnesium (and comes with a spark arrester), no springs are used on the DR.D pipe (it uses the factory’s construction techniques) and DR.D offers a $50 quiet core insert that lowers the sound to current mandated levels.

WHAT’S THE SQUAWK? This is a 99dB muffler system. That makes it considerably louder than the stock 96.7 stock muffler. Additionally, in less than ten hours we noticed brown burn marks on the inside of the muffler can?a sure sign that it needs to be repacked.

This is a five-star pipe because a YZ450F owner will see a greater improvement with the addition of this exhaust system than a CRF, KX-F, RM-Z or KTM owner will for his equal investment, but we knocked a star off because the packing blew out quickly.