Dubach Racing Development, aka DR. D, is probably best known for complete racing exhaust systems. What if all you need is to make your stock Honda CRF450R silencer off-road friendly? Enter Dr. D's End Cap with Spark Arrestor ($99) and the optional Quiet Core ($39.99).

What's cool about this system is it has it all. It comes with the end cap, removable spark arrestor screen, and exhaust nozzle. Add in the optional Quiet Core Insert and you have a very flexible system that allows you to run wide open, spark arrested, or spark arrested with reduced noise. Once installed, all of these options are available with the removal of four screws!

Installation Tips and Tricks

The fit and finish of the DR. D End Cap is excellent, as are the included instructions. The kit comes with everything you need for a quick installation except the tools and drill bit. If you've never removed a stock end cap from a silencer you'll need to know a couple of tricks:

1. The stock end cap is not only riveted in place but also sealed by an adhesive. You'll not only need to drill out the rivets but heat up the silencer to free the end cap from the adhesive sealer. I used a heat gun to accomplish. The instruction recommend heating the silencer up by running the bike with it installed. While this will work it heats up the entire silencer while the heat gun only heats up the necessary area.
   
2. When drilling out the rivet heads, DO NOT drill through the silencer barrel. Drill just deep enough to break through the head of the rivet. Usually the rivet head will start to spin when you've drilled far enough. A light touch on the drill is necessary to avoid drilling into the soft aluminum barrel.
   
3. With the rivets drilled out and the silencer heated up, with a heat gun or other method, use a rubber mallet to tap the stock end cap from tope to bottom to remove. Be patient and it will break loose. I found hitting from top to bottom more effective then from side to side. Also, you can use the wood end of the rubber mallet to insert into the end cap to work the cap free.
   
4. The instructions indicate there will be a ring of packing material that needs to be reused. This was not the case on our '05 CRF450.
   
5. Once the stock end cap is removed install the DR. D End Cap. Make DR. D logo oriented correctly before you start drilling the rivet holes in the end cap.
   
6. When drilling out the rivet holes in the DR. D End Cap use a punch to locate the center and keep the drill bit from wandering.

Results

I tested the end cap in all three mode open non-arrested, arrested, and with the Quiet Core SA insert. The open non-arrested configuration functioned just as the stock setup. As expected there was no performance loss. Obviously, the arrested setup, both the included SA screen insert and the optional Quiet Core SA insert, restricted exhaust flow. However, this decreased restriction didn't demand a rejet of the carb to compensate.

While I use a db meter to test the sound reduction of the optional Quiet Core SA insert, there was a noticeable reduction in the CRF450R's bark. I would highly recommend this insert if you ride in off-road areas. Noise is one of the primary reasons outsiders are working to eliminate our riding areas. Even with the Quiet Core Insert installed the CRF450R had plenty of off-road power.

What's not to like about this kit and optional Quiet Core? It gives you every option you need to go from the track to off-road to woods riding. Each option is a mere four screws away from being installed. The quality is exceptional and installation is quick and easy. It also gives your stock silencer that "aftermarket look". For the cost, this is an exceptional value.

CRF's Only Staff Review January 2005
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