I would also suggest trickflow heads. Not that the e303 is a bad cam but I highly suggest the TFS stage 1(as for off the shelf) over the e303, which is in the same class. If you are worrying about having to notch your piston, I suggest looking into some 1.6 RRs too. A well matched H/I/C is good for mid to high 12s. If you are looking for low 11s, I think a poweradder is the way to go.
Kevin