All, I have been doing a bit of research on cutting down on the intake noise created by two NA 6.354 Perkins. After getting a delivered price of $850 per engine for a Walker Airsep, this suggestion by a contributor to another website peaked my interest. <Make an intake silencer out of PVC pipe. It's easy and it's fun. I am guessing that your intake is in the range of 2.5" diameter maybe 3". Get the nearest sized PVC and a piece of rubber hose to make yourself a boot. Then: Find yourself an 8" piece of PVC, (or 10" or whatever you got room for. Make it 1 or 2 feet long (longer is better). Cut a hole in one side to jab in your 3" pipe cut a hole as far away on the other in to stick out a 3" pipe and Viola... Your motor will suck air into 3" PVC on one end, and it will definitely cut the noise in half. Cost to build about $50.> I was thinking about adding a Donaldson filter in for good luck. May try the theory out on my generator first. Comments? Thanks, Randy