The screen will still let small particles through, and be more restrictive than a proper filter by the way.
These small particles sand down the compressor wheel over time.
I didnt know that at all, but is it true that it quiets down spool with a filter?

 

no way would i put a screen for a filter on a daily driven car. race car, now that's a different story. the paper cone filter will slightly quite down boost but only a little if any. stil, i wouldn't recomend only running with a screen for a filter to anyone.

 

i don't run a screen on mine, never have, but i have noticed little 'rough' spots on my compressor wheel, but i really don't care about my turbo that much and i'm too lazy to fab up some pipe since i have the gay .63/.60 with the funky flange fitting :P if i had a brand new 500+ dollar turbo, i would definitely run a filter

 

well, not only does dirt mess up the turbo, but that dirt gets into the motor if you're running withough a filter. i would just drill out a three hole exhaust flange to fit the turbo flange and have a 45deg. tube welded onto the flange. fabing up a filter assembly for that turbo won't take that long.

 

i need a very narrow filter for my set up.. not much room. 2.0" inlet

 

guys think about it.

most people run intakes on a NA setup. this keeps dirt out of your motor.
now think when your CRAMMING air into your motor with a turbo. no filter, dirt into motor.

not only do you get dirt into your motor, it also goes through the IC as well. but with a turbo, your not just "sucking up some dirt" but cramming it into your motor.

 

The only problem with air filters is the space needed for a decent flowing one. That's why many race cars run these sponge mushroom filters, they flow quite well but the filtration sucks, still better than no filter at all when there is a lack of space.

 

i personally get satisfaction out of knowing that i'm cramming dirt in to my engine and still walking mustangs and almost everything else on the road. i hope when it finally blows, i'll take it apart and find a big mud pie in each of my cylinders, but that's just me

 

k&n for me, I can't see spending money on a turbo kit and running just a screen to protect it.

 

Well, sometimes on some cars, there just isn't enough space to run a pipe for a filter. Like on my project where the engine is flipped 180 around, the exhaust end is right next to the firewall. I just doubled up two screens to try to make the holes smaller. The kitchen strainer method is very pimp imo.