You never want to pull over 200 shot off the rail. only reason is you don't want to lean a bank out and kill the motor. Are there people doing it with 150 or 200 shot absolutely. They are using a BAP or have upgraded pumps as well. Personally for me I would never use nitrous with a 150-200 shot...
Nitrous Outlet makes a kit. Give Houston a call there I believe his number is 866-648-7637 Ext 109
http://www.nitrousoutlet.com/efi-wet-nitrous-systems/ford-systems/nitrous-outlet-11-mustang-gt-vehicle-specific-plate-system.html