Here a post I did on Brutecentral comparing my TwinAir to my K&N. I have not had the chance to compare the Uni yet, but I will and I will post my findings.
I did a couple more mods that require me to re-jet again. Also I did a comparison test of high flow air filters. Here is what I did with the results they had. Soom of you may recall that I have A/F monitors on each cylinder, these do not give me a direct reading but do give me an indication.
1st. I changed from a K&N filter to a Twin Air powerflow kit with the full dome filter. Result was I went from a rich condition to a slightly less rich condition, but still quite safe.
2nd. I changed from a HMF Eco slip-on to a full Muzzy exhaust. Result was my front cylinder leaned out to the point that I had a slight concern of too lean and my rear leaned out just slightly.
3rd. I installed an EHS filter on my airbox. This has dropped me so lean that the bike will barely run with choke fully on. Problem is I do not think I have large enough jets to compensate so I will have to order them.
Now the test of filters. The reason I went to the Twin Air vs. the K&N is because I was seeing a build up of dust inside the carb inlets and a while back someone here threw out a challenge to compare the Twin Air to K&N. I have this kit at work for testing filter conditions in large dust collectors. It consists of a powdered dye and a black light and you put the dye into the inlet of the collector and use the light to look inside the filters and around the outlet side of it to identify any leaks.
I had the Twin Air filter in the machine already so I started with it. I started the motor and ran it about 1/4 throttle and sprinkled some of the dye into the airbox inlet and let it run for about 5 minutes. I removed the filter and fired up the black light. The outside of the filter glowed like an LED, but the inside there was nothing and in the carb inlets nothing.
I then installed the K&N and ran the same test as with the Twin Air. When I took the filter off and put the light to it, it glowed a little on the inside of the filter. What shocked me was when I shined the light on the carb inlets. It looked light someone put LEDs in my carbs.
My conclusions are this:
1.The Twin Air flows much better than the K&N.
2. The Muzzy flows much better than the HMF. I expected a gain on the fron as I was using a stock front pipe with the HMF. The Muzzy sounds awsome too.
3. The EHS cover mod is just incredible for power gains and will complement my 840 kit beautifully.
Test, Finally put my suspitions to rest. The K&N is just not a fine enough filter for the type of riding I do in the dusty condition.
Regretably, I was not able to get any of the dye to show up on my camera so I can not show the results.