Yes there are fast imports that will walk over v8 cars. Yes there are fast v8 cars that will walk all over imports.
What you need to remember is that the truly fast imports are very few and far between. This is mostly becaue they cost a lot to build. The majority of the asshats concerned with their imports being fast (ie highschoolers, wiggers, and azn wannabees), don't have the capital to build the imports properly.
Example, there is a guy here with a MX3 Presidia that hung a bobcat turbo of all things on it. Add one loud blowoff valve and voila...dude thinks he is fast. Car runs a 15.5 at the track. Cars that come stock with 100 hp are not worth modifying. A turbo that even adds 50hp costs around 4k.
Another guy in a Delsol did a twin turbo setup here in town. His license plate read "Me too fast". By most accounts the car ran high 11s, which is definately respectable. Unfortunately, he blew all his money on top end and didn't bother with bottom end or fuel management upgrades. I saw his car before the engine grenaded huffing thick black smoke out of the exhaust and it sounded like there were marbles in his engine. If he had had another 30-40k, that thing would have been crazy, beut being just out of highschool, the dude just didn't have the coin.
I priced a "10 second car" import build as I was interested in building one, but the cost to do it right came in at close to 60k. I am going to have 35k into my fox and it will run 10s all day long reliably.
My cousin has about 25k into a 1966 Chevy 2 4 door station wagon, and he runs 10s all day. When that thing literally stands on the bumper and there are spark flying off of it, people notice.
S2000 and cars like that are generally driven by older, more mature individuals who aren't concerned with whupping some dude in a 5.0. And the young kids that drive them are using mom's or dad's or grandpa's car and are more likely to wreck them into something becaue they aren't used to it.
A buddy of mine imported a Skyline from Japan and that cost him about 12k. The car is in rough shape, but I gotta admit, that thing pulls hard and sounds pretty crazy while doing it. It pulls just as hard as my stock fox coupe with both cars being NA. Plus it is right hand drive which rocks.
So if you get owned by a dude in an import, congratulate him of having a quick car. If you get beat by a rocket powered outhouse, shake the man's hand.
Fast is fast no matter what the badging on the vehicle is.