Yesterday I got my header installed + cat delete!
My old exhaust set up was DC header, OEM cat, Tanabe Super Racing Medalion. Sound was near stock-quiet with the silencer in place, and sounded aggressive but not too loud without.
The plan is to install my new header + delete the cat. The cat has been passing the honeycomb element out of the muffler and so I've decided to just replace w/ a straight pipe. Also, this works out because the header is for a bb4 and is longer than the type SH header, and so by using my own piping I can bridge the gap between the header and catback to make everything fit.
The new parts: Mugen header, 2 ft 2.375"OD/60mm circumference stainless steel (18 gauge / 2.25"ID), 2x O2 bungs, 1 set of HELP! anti foulers to avoid CEL from cat removal, 18x1.5 bolt (80's toyota oil drain plug) to plug O2 bung on header B-pipe.
Pipe: $59.23 <-

(
Burns Stainless)
Two 02 Bungs: $4 (Muffler shop)
Pack of anti-foulers: $4.99 (Autozone )
18x1.5 bolt: $3.29 (Napa)
O2 sensor (bung) snow man:
What it should look like:
Welding done:
Installed:
I haven't driven much yet, but so far no CEL w/ the anti-fouler mod

The most noticeable thing is that my car is super loud now in the cabin. I haven't tested it w/ the silencer out, but I dunno if I want to considering the volume as it is now