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.