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Old 11-15-2010, 07:03 PM   #13
The Griz
North Forest Rider
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Joined: Nov 2008
Location: Minnesota
Oddometer: 3,787
Originally Posted by JoelWisman
This is why you will NEVER improve HP and runability through airbox mods, filter mods, header mods, or fancy slip ons. You may increase noise, or peak HP, but always at the cost of mid range torque. No aftermarket manufacture has the wads of cash or engineering brain power to design componants that work better then BMW original equipment.
Again, as I said before, very thorough and complicated post. However, folks, take some his opinion-based statements regarding this bike with a grain of salt, especially what I've quoted above. What I've quoted above is simply false. Runnability and power absolutely CAN be increased with airbox mods, higher flowing air filters, and higher flowing exhaust systems and headers. However, once these changes have been made and items have been bolted on, the owner MUST re-tune the air/fuel mixture to match the change in higher intake and exhaust flow. Otherwise, the engine will run much too lean resulting in hotter running temperatures and reduced power. This may be what Joel is talking about. However, again, in order to reap the benefits of intake and exhaust modifications, you must richen the air/fuel mixture to match. The onboard ECU will do its best to compensate and richen the mix, but unfortunately it cannot richen the mix on its own enough to reap said benefits. Contrary to what Joel says in his post, you CAN gain some power and better 'runnability' with airbox mods, higher flowing air filters, higher flowing air filters, and a higher flowing exhaust. But again, you MUST richen the air/fuel mixture enough in order to match the extreme changes in intake and exhaust flow you've made. Otherwise you're doing more harm than good. The only way to richen it enough is to manually tune the bike with a Booster Plug or Accelerator Module. These items will richen the mix enough to reap the benefits of the add-ons we speak of.
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