Any yanks present?

Depends what you want to change really. Broadly, so long as it's not going to kill every pedestrian you pass, and meets the exhaust emissions levels, you can do most things. Why d'you ask anyway? I'm all interested now! (nosey bastard).

Some states have strict emissions tests, some have no emmissions tests. Some have a sort of MOT, like does it have tyres and a steering wheel, and some don't even limit their residents right to drive that strictly.

Just thinking that I could move there in a year or ten, and wondering if the car could come too...

Probably. Where abouts are you thinking of though? They have a similar scheme where individual imports are allowed - that's how Bill Gates got his 959 street legal apparently. I suppose you'd be best off asking in some group with a higher yank content really! In Canada you can get pretty much whatever you want in - if it's anything like it was when I was there, you don't even need insurance if it's registered in Alberta!

Dunno. Fancy doing a bit tour of Amerkia in year or two, but at the minute I could fancy New England.

That's show or display vehicles apparently, and that means your serious homologation specials etc. - less than 500 ever made. OTOH a 1.8T MK2 Golf would go well and hit emissions regs...

Ah, I see.

Well, couldn't you just make one over there? I don't think you'd have much of a problem with stuff sourced from the states.