you will need to play around with the a/f setting's,
before i changed my Main jet, i had done tip #3, Iridium plug, and a custom air filter, and i was at a full 3 turns on my a/f.It was Tuned by a pro from Yamaha factory abroad. It's not really recommended to not use a filter, it would be better if you just modify it.
for eg: soak the stock filter in water for about 30 minutes. then use a cutting blade ( not a kitchen knife) something from hardware to cut out the paper element. Don't remove the metal plate, then but some Scotch Brite Brillo pad ( used for scrubbing pans ) cut it to fit into the Plastic housing of the stock filter, Use two pieces of the Brillo. then your done.
after that it's just fine tuning your a/f and idle to the right setting for the best performance.
Try it bro, for your safety, you don't want to get some dirt or thick dust in your carb. not goo! ok? just try it.