Import regs

[LuS1fer]

No. Loads of American cars are imported in modified form. Also, as I have just found, the SVA form divides cars into Classes and "left hand drive" is Class N so the standard SVA test applies. Any other cars are Class R and have to pass an enhanced SVA test and comply with loads more stuff including radio frequencies on alarms. It's worth getting a form from VOSA just to have a look.

However, the import declaration form asks you to detail any mods to the car and their value so they can tax you on it. In other words, if you had a twin turbo conversion done in the US, the theory is that you would have to declare that and pay the tax on the value.

[blackzr]

Due to the fact that Jap cars are built to different (lower) certification standards than European and US cars they go through a different SVA test.
Almost all EEC vehicle safety standards are met by US cars so it really is a breeze to get them into the country.