Cuttign the firewall. Yes, I did, but as you know, my baja is pretty cut up already so it wasn't a hard choice. For me, metal was cheaper than building a new intake. I've seen some run a 180deg fitting on the intake and keep the firewall, also it's pretty common to flip the intake manifold. If you go with the ten degree kit, you will either have to cut the firewall, reverse the intake because there won't be enough room for the 180deg fitting, or you could consider moving the engine/trans back a few inches if you're going for longer arms. Anoher option for the die hard off roader would be to cut a circle and just run the intake inside. Flipping the intake involves rewiring (reversing) the wiring harness on the engine, plus relocating the alternator. There is lots of information on the net. Search "ej22 flipped intake", then click images, I'm sure it will show you. (I found this link with some good info --> http://www.vtpete.com/vw/labels/engine.html
For reference in this picture... The top of the aluminum adapter plate is about level with the package tray. The front of the intake (blue towel) is about 2" behind the factory firewall.
Heat... Yes. Many options from crude to refined, but here is what I did. http://www.shoptalkforums.com/viewtopic ... &start=210
I just ran a few hoses through the factory air ducting to under the rear seat and plumbed the hot air into the factory channel. This is a military surplus Jeep heater, $60 or so. It works okay on chilly mornings, but can't keep up with my uninsulated bug body at 10 degrees F.
On the next page of that build is a picture of what I could cobble together with the factory subaru heater parts. I haven't installed it yet.