I've thought about this for a while... There are some down-faults that I have come across... 1. Using two intake and exhaust manifolds... Upside... Could get pretty decent boost off of the stock ECU... Downside. If a turbo goes out. One of two things could happen. Different wear on three different cylinders. Causing a blow in gasket due to uneven pressure. Or blowing your head. 2. L28E motors were not built for a turbo charged system. Hence all kinds of bad would go wrong. 3. ITB's with two different intake and exhaust manifolds. Same problem as number 1 up there. It's not worth it to dump a lot of money into parts that need to be custom made. I remember 1 fast z... He used ka heads and put them all together. Hence a cross flow head with less heat. But that's my 2 cents.