amuse STTI exhaust with HFC or FI long tube headers?

zuperman 370

hey guys, soon ill be getting my amuse STTI exhaust, its on order and should be ready this month hopfully

my questions are, what combo do you guys think i should go with for that set up, HFC's or FI long tube headers? im not looking to make it sound raspy, because from what i read the amuse has an exotic tone to it, so i wouldnt want to mess with that, i know the hfc will make the sound deeper, but will the FI make it raspy?

my second question is which set up will give me the better gains?

if i install the amuse first and either the HFC or FI long tube headers at a later stage, lets say for example after a couple of months, will that take away from the gains? does it make a difference if installed together at one time or seperatly ?

And last but not least which set up will sound the nicest, again from what i read, the amuse sounds amazing so i wouldnt want to mess with that by going with the wrong combo?

and a side note, just to make sure the FI long tube headers eliminte the HFC right?

Thanks guyz in advance.