After some research I've found, out some stuff about the H6 swap. engine wise you can swap it right in mount it up to our stock engine mounts and our trans will bolt right up. You have to do a harness merge. and mod the radiator a lil so it fits. then you can start throwing money in to it and get some crazy high HP with a lot of reliability. so far i've seen 2 or 3 cant remember if one was the same or not. But atleast 2 of the newer 3.0s reach over 600 WHP. THats super charged with only 22PSI that in my book makes it worth the extra bit of cash and modding to swap it in. I even think You may be able to swap in like the sti dash and hook it up that way. Not really sure on that. But it could be. the best way to do that swap is to do a full engine trans are rear diff. but if you cant get it all at one time you can get anyone of them and put it on before you got it all.
I will go and try to find links to some pages about the swap. Brokn. you can go through this and take what you will out of it if you wanna add info to the FAQ