Anthony have you looked at finding the stock single turbo and plumbing from the later model 1JZGTE? I don't know how compatible they are but i believe the turbo is a CT26?? Your 1GGTE has CT12 turbos right? If you decide to keep the twins can you just fit the larger CT12A turbos from the older 1JZGTEs? Isn't the IS200's engine block basically the same or originated from the 1GGTE? I have seen a few turbo conversions onto IS200s...guess it comes down to money. 5 speed? try a Jap wrecker...ask them if an IS200 6 speed will bolt up just for something different.