if its a single turbo kit, it doesn't mean its spools quickly. it depends on the trim on the impeller side.
however, there a reason why people go single turbo,it is big power. that's what they are after, they are not concerned per say with drivability of the car. that's why turbo supras and skyline that want 1000 horsepower, go to single turbo. example why porsche went from 930 single turbo to 993 and 996 twin all in the name of drivability. if anyone of you have ever drove a 930 turbo you will understand what I mean. when you first take off, there is no power but mind you as soon as that turbo kicks in, make sure your straight if not you will be spinning. also do a search on turbo and boost, matter of fact pick up the book called Maximum Boost by Corky Bell, its explains how more psi is not always the answer.