new exhaust

Alright, so I'm gonna be gettin a exhaust soon. I got a 305 it sucks but it gets er done right now. I'm gettin some older headman headers that might work that I'm tradin a buddy some kenwood speakers for. If not then I'm buyin some hooker headers from a local shop I'll be puttin em on my self and drivin it to the shop straight headers which will sound nice as hell and mean. Then I'm gonna run true dual's out to before the axle and have em either exit the sides or turn down at a 45 out twards the sides but under the truck, I'm thinkin flowmaster 40's or maybe some magnaflows I'm not sure. No cats which will be nice to. Should I buy headers with a o2 bung or put it on one the pipes? Does a x-pipe make any difference? well yea thanks for any input.

Peace,
Wil