Headers are definitely on the low end when it comes to price vs gain. However, if you are planning on staying NA, and want to get the most out of your motor NA, then they are a must. I've got the same exhaust set-up as you (F.I. TDX CBE w/ 18" res) and I went with the F.I. LTH's mainly for the mid-rang advantage of them over the peak whp. They are definitely a quality product and Tony, as many have said, is great to deal with. Here is a short clip of mine in the dyno in case you are wondering about sound...
fiya. - YouTube
Hope this helps in you decision-making