I wish someone would run before and after Dynos on that.
Decreased surface area to draw air thru, I spent several hours reading about intake theory, since intake relies on suction, an obstruction is a bigger limiter of air flow through the motor than the same obstruction in the exhaust, because the piston is pumping air passed it.

Optimum intake design has sufficient volume between filter and carb to fill the cylinder. Careful work CAN create a pressure wave standing in the intake just waiting for the intake to open, but that would, unless variable, enhance a small RPM range.
The science of intake design has only barely been approached on this forum..
I don't remember what all I learned, but I increased the volume of the air box. I had a Stage one cam, Supertrapp with 14 disks ,jetted carb,
Zero to sixty times were ever so close to six seconds and I had not lightened anything.
I did use a KN filter but wouldn't again,,, money wasted IMO.
I would not spend the money on a Supertrapp, unless someone does dyno runs proving the Trapp IS sufficiently superior to justify. $400.00 vs. $20.00
money for a muffler. Besides, the Trapp is ugly and the Dyna looks good.
Of course, dyno runs or timed runs, something besides Seatof the pannts,

efficient air intake design for large single cylinder engine

Ever try to drink a malt through a skinny straw?
The more square inches the air filter has, the easier it is. Remember,intake isnt Shoved in. Exhaust is Gonna happen, but intake can easily be restricted.
The manifold volume between filter and carb , for best results,, according to what I have read and can't find now,  needs to be at least the volume of the cylinder. Or, as we see on competitive stuff, very low restriction.
If looks is the goal, just be aware that some aftermarket filter mounts can block important passages on the carb.
Several here know what works, sorry, that is all I know.

Neilap wrote on 05/17/15 at 17:42:45:


Ram Air will sure confuse your carb....unless you connect the vents to it as well.  Most ram air/scoop setups on cars places the entire carb in the housing for the ram air so the entire carb is under the same pressure.

Get too much pressure.....and you will be pushing the fuel back up into the gas tank on this gravity flow system!

It is mainly for looks. The only 'performance' thing id like to do is get the pipe made out of metal to look nice and stay cool. As we all know black absorbs heat and shiny rreflects. But as for myself i have never felt rubber actually get really cold. I am a very strange thinking individual lol.