Tennessee. The greatest place ever to be a car enthusiast. Emissions? only if your car is registered in a county with a big enough population (mine is registered in a county with a smaller population so my car is street legal
). Illegal modifications? Rather the question should be, is there actually anything illegal? As far as I know, laying frame is about the only thing you can't do. No cop will ask you to pop the hood or anything. I've revved in front of a cop and he left me alone. Imported vehicles? **** if you can manage to get it registered in some way, you can get plates and roll on the streets no matter what side the wheel is on. Skylines? Just say it's a kit car or a 240SX. RHD EK9 or EK4? It's a Civic so it's an automatic pass! Aftermarket Turbo's/Superchargers? Again, cops don't give a **** plus there's no laws against it. Suspension and noise levels are it. As long as it doesn't lay frame and you ain't running open header, your pretty much golden.
Pretty much the main requirements are, the vehicle must have working headlights, taillights, and turn signals. Depending on vehicle age, there are other requirements such as safety (which prevents you from registering a R33 or R34 as anything other than a kit or 240SX, R32's age may get it past this). If it's registered as a kit, it pretty much bypasses all safety laws. That's why Caterham's are sold only as kits here. Vehicle age pretty much bypasses all that too. once it's past a certain age, it no longer requires emissions checks as well in the counties that require it.
Tennessee rocks. Lots of open country back roads too for good corner carving. There may be no mountain passes but by golly, these roads are right up there with em.
Only downside. No road course race tracks aside from the Nashville Super Speedway road course which ain't much.
. hahaaa man out thinks machine again! 
