Dude, if the car WAS a V8, it would have different STANDARDS for smog checks anyways! Every car that has a different motor classification has a certain smog rquirement/standard. Anyways, if you turbo a smaller engine to make the power of a larger one, you sacrifice mpg..........................They can get the power out of a V6 without needing to make a V8.......the '87 GN had about 345 TQ......If you can stomp on the V8 vettes, why upgrade to a V8 and turbo it? If you did that, people would see this and know it can stomp the vette. There is a term called the "corvette rule". Basically, for many years, GM never wanted to have a car that can beat out a vette. The LS1 motors in the new fbodies are even underrated to show more of a gap between the C5 and fbody, to justify the more $ spent
Anyways, Buick could not cover up it's performance if it unleashed a V8 that was turboed because it would be known to be faster than a vette. I doubt GM would want Buick to produce a Turbo V8 because of the vette image. There is more than "economy" factors here at work........