There haven't been gray-market cars brought in to the US since the mid-80's. I believe it's both due to emmision laws and crash-worthiness tests for the US market. I believe the Japanese emission standards are similar to the US standards however.
You may find it very hard to get the car registered in the US, and also to get it insured. Good Luck, it would be a fun car to have over here, as I believe they are right-hand drive.