is it worth it? does it improve hp,tq.? when installing these would it be best to buy the rail, injectors, and regulator at once, or could i install one or the other and wait to install the others?

what would be the best injector size and modle?

 

by looking at your sig you don't need a rail or high flow injectors but then again it does say you are awaiting a JRSC, if you are then yes I recommend both. I don't recommend them for stock applications unless you are going the FI way and require more fuel to mix with the larger amount of air being shoved into your engine. With an FPR you must, however use a fuel pressure guage to adjust fuel pressure accordingly.