Welcome to the forum Mike.

There are a bunch of vendors that sell all kinds of intake parts for the Evo. You can do anything from a drop-in K&N filter to an entire intake pipe with upgraded BOV placement and upgraded IC pipes.

Check out www.dejontool.com for some great ideas there.

As for the gauges, boost is a must but A/F and EGT really aren't needed. At least not yet. I've never had a working A/F or EGT on my Talon and it has been just great. You just have to be careful when tuning the car.

The factory BOV is still plastic, so it will leak eventually. A 1st gen BOV is a great cheap upgrade and works well with aftermarket IC pipes.

Nice to see you in the turbo Mitsubishi world :) Have fun. Come to the Shootout.