Ranatsu, how many oil changes do you do prior to the first uoa? If Fe, Cu, and Si don't improve on the next uoa I would go back to the stock intake. What are the driving conditions? Any track? Any other mods?
As long as you're letting a little oil drain prior to taking the sample as Blackstone recommends, and also don't wait until the end of the drain, you shouldn't be getting any dirt from the Fumoto. But you can always get an oil sample pump for easier sampling and less chance of contamination.
http://www.blackstone-labs.com/vacuum-pump.php
-Dennis