I would guess TRD headers...
The TRD headers are tuned and optimized for the TRD cat back exhaust.DW owner here with the TRD dual exhaust.
Does anyone make a properly tuned header that fits this exhaust system ?
The TRD duals are tuned really nice so I don't want an aftermarket set that screws it up and I don't want to get rid of the TRD's if someone makes headers that retrofit...
Unfortunately Toyota decided that the '06 model year doesn't deserve any perf mods. I am also a Chevy 1500 owner and took it for granted that everyone had tons of mods ready to bolt on. WRONGThe TRD headers are tuned and optimized for the TRD cat back exhaust.
I have this combination and it is sweet. The only thing I would
recommend doing before installation is to have the headers ceramic
coated. The stainless steel looks nice when you first put them in, but
the finish degrades to a "muddy water" like sheen after about a year.
The ceramic coating will prevent that and also lower your underhood
temperature a ton compared to uncoated headers. There is a place
here in Nashville called Nitro Plate that will do the job for $225. It is
money well spent and next on my list.