I don't think it will be a "safety" issue from what I've heard (and observed so far), but I definitely do think a proper tune will be in order once all the major parts are on. My plan at the moment is Stillen's G3 intake, headers, and cat-back, with the Berk HFCs. However, right now only the headers and HFCs are installed. The car will be dyno'd and tuned once it's all in place.
I got under the car just now for the first time since getting back to Houston (with floor jacks, etc - what a pain
). I went ahead and retorqued what I could easily reach (basically everything but the actual header<->engine nuts), and found a couple that turned decently (half a turn on one, a bit more than a quarter on the other). Test drove it after, and much of the rasp is gone. What rasp is left now only kicks in under more demanding circumstances (full throttle or near to it and 5k+ rpms). Re-torquing the header bolts will probably get rid of the rest.
I also got my first good look at the cats during that, and the metal has discolored significantly now that it's been subjected to exhaust heat. They had a plain stainless steel color on install, they're now a deep burnt copper to also dark brownish all over. I expect this is normal, and that it probably explains the smoking during the first warmup. Someone let me know if you don't think so
Later in the weekend I'll probably team up with someone to have more jacks and jackstands available and get under there to retorque the header bolts.
(Oh, and with less annoying rasp I was willing to push the car a little further on this drive, and my patented Butt Dyno definitely now says it feels the difference, at least in the upper rpm range).