im still dicideing weather to do this but will there be any increase in HP

 

Absolutely useless to do it unless you have done some headwork and cam at least. Plus intak throttlebody and exhaust, dont waste your money.
The only hp gains that it will make is if you have a bunch of other mods to get your motor breathing better, and then it will only allow you to get what your previous mods should allow for gains.

 

be completely pointless unless your pushing 800+ hp...

bro is pushing 420 and he is still on his stock rail/fpr

 

FPR... yes if you can use it correctly.
Fuel rail....no, unless you consider bling a difference.