Why? Just run stock rail with the right injectors and a good EMS> Rail does nothing but look pretty pretty much. Get a good off rail FPR like aeromotive if you're going to invest in rail/fpr area. Even then you can runt the stock FPR up to 500-600 whp no problem if it's in good shape. Your next logical step is a good EMS or a good camshaft after that On topic of max hp with stock SR FPR 500 WHP all day - . I've personally done it.
Invest is a Q45 TB instead.