OK, im not paying 70 dollars for an air box lid...
instead, i am going to put a 4x4 vent in the top of the air lid...
will this give sufficient cooling or do i need more holes?

 

yes, you can drill or cut holes however you prefer. that will help the bike out. for me, it was mainly noticeable in the low end. when modding the lid, you should go up one or 2 sizes on the mainjet depending on how much you mod it.

 

see i dont know if i should put more holes in it then that...
should i?
and should i do anything else reguarding intake besides K&N jet kit and uni filter?

 

I got an aluminum airbox off ebay for $65.00 and I love it! It looks awesome and the welds are beautiful, the sellers name is "granitegear". Buy one, it's well worth the money. Oh yeah, it relocates the battery too.

 

well its not going to 'cool' anything off, infact if you dont rejet it it might make it hotter lol. but it will provide a slight increase in performance, some throttle response maybe. if u mean a 4 inch by 4 inch square hole in the middle of the lid, i think that that would be fine. you can do more if you want. i would prefer to drill many small holes instead of one big one because it may help trap large objects such as leaves etc. from entering the air box. hope that helps

 

are these available for 300ex's or just 400's?

 

yes, the number and size of the holes you put in the air box lid will depend on how much air along with dirt and other particles you want in the airbox. i don't think you need to do anything else to the intake.

 

check ebay, try "300ex airbox" 300ex air box"

 

Where do you get $70 for a lid??? A lid is about $12! Maybe $70 for an airbox AND lid???

My lids are full of Uni/White Bros. filtered vents. !" round plastic inserts, with a filter. You will need to rejet any time you increase airflow.

 

ok guys, well im not just drilling holes in it, im going to buy some vents for it today and im gonna put an aluminum plating underneat it for the vent to slide into. Its not going to be rinky dink. Im also getting some light filter paper for inside the vents, so it wont let leaves n stuff through...

other than that, it is a good idea?