Multiple questions on exhaust system

[Korgot]

Sentra 2005 1.8SE

Hello guys !

Thanks to the info I found on this forum, I decided to change a couple of parts on my car, starting with the CAI, the header and the exhaust !
I choosed the Injen Cold Air Intake and I'm almost sure on the header, a Weapon R. But this leads me to my first question:

What kind of header is better ? A 4-2-1 or a 4-1 ?

And with changing that, I want to change my exhaust. I'm looking for a good sound (not these high pitch garbage-can sound Civic). Somebody here told me to put a 18 inch resonator because the laws are really strict here, but as long as my pipe and muffler doesn't sound like a Harley Davidson, I should be fine. So here is my second question :

Do you guys have an idea of pipe/muffler I could use for my Sentra 1.8se ? Because with all these dual loop mufflers, catbacks and other terms I don't understand, I don't know where to look ...

Thanks in advance and a big thumbs up for all the help on this forum. Joined a week ago and already found most of my answers !