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Found this interesting write up on another forum: It shows how complex & how much design work goes into building the airbox to make it work properly on our bikes, makes you think twice about doing any mods to it.

The configuration of air intake system.
To achieve the maximum trapping efficiency while giving prioritising complete motorcycle packaging, the air cleaner is composed of right and left ducts and two air filters. The air cleaner box is a three-chamber construction positioned across the main frame behind the steering head pipe. The length of connecting tube from the air cleaner box to the throttle body was set differently for each cylinder (#1: 110 mm/#2: 160 mm) to cope with the uneven intake intervals of the 270 deg phase crank.
To cope with dusty air in off-road use and to ensure a long service life of the air filter, the intake ducts were located in the headlight side cowl, and two viscous air filters having a filtering area of 1,200 cm2 were provided in the right and left sides of air cleaner box.
To keep intake noise at a low level while avoiding a weight increase from use of devices such as a flap in the intake duct, an intake duct having a diameter of 25.2 mm, which is as small as those of small displacement engines, was applied. A tapered duct, in which the diameter increases from 25.2 mm to 50.6 mm toward the downstream of air flow, was also applied to reduce suction resistance and achieve the target power output while ensuring drivability. Further, the overall length of duct was set at 286 mm to increase power output by the inertia effect from resonation in the intake system.
 

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I don't think to upgrade the internal airflow (i.e. upgrading air filters) count as modifying the integrity of the airbox itself.
 

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No it wont, just give you more maintenance keeping the after market filters clean
Depends.

If you ride off-road a lot, stock or not, you'd want to check & clean/replace your air filter sooner than the suggested interval. But if all you do is ride pavement you can perform your maintenance every 9K miles which isn't considered that much "more" than stock IMO. I think stock is...every 12K? I forget.

Besides, it's cheaper to clean than to replace and provides better air flow. However, I will say this...in my experience, there are more downsides than upsides to upgrading the filters. Such as it allows too much airflow (some times the filters will allow more dirt & grime through than stock), oil residues, and cleaning & oiling the filter is a PITA.

Storytime: back in late '96, Honda had just redesigned and released their new 1997 Honda Prelude. I was one, if not the first, of few owners when they released it. I immediately took it to AEM and asked them to use my car to build a cold air-intake for the new Preludes. I recall the owner asking me if I plan on racing it. I said no, and that it was going to be a daily driver plus I just wanted to increase HP. He replied, "yeah we can do that but there is nothing better than stock" and went on to explain the benefits of leaving it stock. When he said this I was :surprise: and confused. Why would a reputable aftermarket company say such blasphemy?!!! Fast forward 16 yrs, I understand what he meant.
Let's just say if you're not racing professionally, pushing the limits of your stock parts, and/or at the front of the pack looking for that back-to-back championship :wink2: it's not worth it.

With that said, I will say this...gad dang those aftermarket parts look & sound good!!! :grin2:
 
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