i dont think it will hurt a v8 but 4 bangers and some 6 need backpressure, friend of mine was a toyota mech. for about 18 years untill health problems wouldnt let him, he told me a story about a guy who bought a new tundra or tacoma dont really remember but he cut the exhaust right after the y pipe and broght it back within 10,000 miles becuase the engine was using oil like no other, they had to replace the engine, put the exhaust back on and the truck came back again with the same problom and no exhaust, no warrenty this time tho. He said he didnt think that guy was right in the head.