John,
Can you show me a picture of the pleated top?

Ademon,
How tall is your current air filter?

Thanks for the replies.

The K&N websight showed the same stock size air filter for a 340,383, and 440. Now I am guessing that if a 2.75" tall unit is good for a 440, and I am currently using one on my 340, then I would not be missing much by going down to a 2.12" tall unit.
----------------------------------------------
I found this on the K&N Websight:

The usable portion of the filter is called the EFFECTIVE FILTERING AREA which is determined by multiplying the diameter of the filter times Pi (3.1416) times the height of the air filter in inches, then subtracting .75-inch. (We subtract .75-inch to compensate for the rubber seals on each end of the element and the filter material near them since very little air flows through this area.)


A= CID x RPM divide by 20,839 = effective filter ara

My combo: 340 x 5800 divide by 20,839 = 94.6 sq. inches

Current Air Filter: 12.5"od filter x 3.1416 x 2.75 (-.75)= 107.2 area

2.12" tall: 12.5"od filter x 3.1416 x 2.12 (-.75)= 82.5 area
Minimal Air Filter: 12.5" od filter x 3.1416 x 2.50 (-.75)= 97.4 area

I can only go down to a 2.50" tall unit which may not be worth it. I will next measure the inside of my stock 340 air cleaner housing to see what the max diameter filter that can fit and see if a 2.25" (or so) filter would be enough flow.

-------------------------------------------------

I found two sizes that might fit depending on the ID of the 340 housing:
#E-3740: 14.0" dia x 2.31" tall [@ 100.8]
#E-1580: 13.2" dia x 2.5" tall [@103.3]