I've searched for this and couldn't find much.

I want to try and toss my airbox lid and bore a 1/2" hole into my exhaust baffle today (and run that till I have the money for a new filter and exhaust system), but I don't know exactly how lean this will make my bike, and what I can do to even this out till I get a new jetting kit.

I live in Hawaii btw, at just about sea level.

 

It will make the already lean machine - leaner! I'd wait until you put in the jets - patience my friend.

"If my calculations are correct, when this baby hits eighty eight miles per hour, you're gonna see some serious sh*t." - Doc Brown

 

Well, I popped off the airbox lid completely today. It actually SOUNDS like a dirtbike now!

BRAP BRAAAAAAAAAAAAP!

Haven't noticed much a performance increase though, but then again, I ran out of gas while I was taking her for a test spin, so I didn't get much of a chance to open 'er up :P

If anything, at least the cagers know i'm there. At stock, i'd get worried that nobody could hear me, and that they didn't know I was there.