DC headers are good I run one myself...my only recomendation is to have the shop shave off the lower mount tab before install as it will just end up breaking anyways in a few miles and you will have to jack up the car and remove the tab anyways....save the time and annoyance and do it ahead of time.

Suspension is pretty partial to the kind of driving you do....straight line would reccomend different springs/struts than cornering would and whether you just want style or actually looking for performance out of them too.