Good luck getting that big S91 to fit, my builder had to mod some pipes and stuff to make my S85 to fit where it is suppose to, again you have a newer version of the kit. I am not trying to high jack this thread but just letting you know its close enough of a fit as it is and we all know not all cars are exactly the same. Of course my car is a 1995 w/Ls2 and builder finally got everything to fit, but the first two pics show of the engine/turbo clearance problems. The third pic shows more clearance. He had to end up cutting pipes, etc. For sure interested in how yours will turn out. PM me if you need more details of how to get it to eventually fit if yours does have a problem fitting, I hope it doesn't.
Engine Clearance Problem Pic 1

Engine Clearance Problem Pic 2

Now with the pipe fixed to allow the turbo to fit

Kit fitting

Another pic wth kit fitting.