Want to mod my Nismo but soooo confused

MoverShaker

I've read so many different opinions on mods that I'm left confused. I've got a 2013 NISMO and would like a little louder sound with a little more power.

I'm thinking of adding:
STILLEN 409 Stainless Steel Headers - Ceramic Coated -
STILLEN Stainless Steel Exhaust Systems - Dual Wall Tips -

My confusion lies in the best bang for the buck and I'm also worried about adding either one mod or a combination that effects power negatively somewhere along the power-band.

For instance, I read somewhere this morning in a thread that said changing the headers is bad place to start because you don't get much of a power gain.

I've also read so many conflicting opinions on the stock cat back that I don't know if changing it is even a good idea.

Or should I just go with the Visconti tuning for $1k? This option intrigues me.

Ugh!