No, do not get headers unless you plan to supercharge it later. It will feel like an absolute pig except for during WOT. Those primaries are so large you will get little to no exhaust scavenging with a N/A 3800.
Start with an intake. Then get a DP. If you still want to do more, a Plog is good. After that, go with a TB and HV3. At that point the only thing you have left to do other than supercharge or turbocharge it is ER rockers.
If you get that HV3 insert and decide to supercharge it later, isnt that a waste?
That's why I told him to pretty much decide what he wants to do now.