my 04 EVO is stock with the exception of a MBC set to 19psi. I tried a few different things with the runs... nothing had a major effect. Seems like the car runs best with the stock filter and no lid (at least in my case). See below...

AFR is pig rich, needs a "good" tuning. let me hear your comments.

 

I don't know how to make the pic bigger, best numbers are 257.62hp & 269.48tq worst numbers are 249.08hp & 251.15tq

 

Yeah, they seem to gain just a teenie bit of power with that lid off on the dyno.

 

If you take that lid off then you should tie it down somehow, you don't want junk flying in there.