If you have dynos charts and flow analysis to prove that the 2GRFE stock exhaust is a bottleneck, please share. Otherwise, i would suggest you look up MKC ypipe .Not so much about opinions as just informing the average joe that spending 300 bucks for a 5hp gain (to which they wont feel) is pointless.
IDK who Area47 and 2quick is or their experience, OEM exhausts are restrictive. Dyno runs have proven this time and time again. So not need to argue this mute point.
But as a guy who has built engines and a race car, im only speaking with my experience.
Ps - I see ur a Honduh guy, and i can understand ur rationallization since the have a zillion parts for b16, b18, k20s, h22s, and even j30 engines hella cheap and readily available. As you can see by ur query of trd parts, thats not the same case in camryland where even a bolt on exhaust is hard to find. I've built and tined my own cars as well and while its fun to go custom everything, to most this is their DD so ppl prefer bolt ons (i know i do, especially living in CA with the smog nazis). Im not deliberating the merits of a a $300 air filter (i didn't buy one myself), just noting it as a viable option. I guess if the OP continues to be selective on what he notes as "available", i'll just supplement the info in my build thread.