It can be done, but the turbo engine may have used a lower compression piston and probably a differant camshaft, which might make the engine a bit of a "dog" compared to a regular E15. The turbo version had a whole lot more sensors and plumbing than the non-turbo version, as well. The turbo N12's were fairly rare and I believe every one I worked on was black. They were more prone to driveability issues and oil leaks, it seemed. They were pretty quick and it's a shame that someone decided to convert it rather than fix it properly.