As you know, turbo's being exhaust driven components. By listing the cars you have, they are all V motors as we know. They all run a balanced system with a certain liters of displacement pre side to drive each turbo. Through fitment and design it's more efficient to run sperate exhaust manifolds for V motors vise wrapping it around the motor and porting through a single exhaust. The idea is to get the exhaust gases of the motor out as quickly as possible. That being said, not one of those cars or manufactures is quicker than the top Full weight Street USA Supra's. The Supra people go single for one reason over twin and that is for the cost. No matter how you work it, buy one turbo or two. It's just cheaper and can still yield the same power band. By simply having a straight or inline motor, they drive any size turbo with all the motors pistons and lag is not so much an issue.
