Header/Cat Advice (wanted)

Hey y'all, sorry if this has come up before: i searched for a while and couldn't find it so send me a link if it has.

Anyway i got an 06 taco w/15 miles on it. Been looking forward to the clutch blowing out so i have an excuse to do the exhaust and header, blew out the clutch 2 days ago @ 110k. I just ordered the banks monster exhaust cause it was on sale and free shipping and i've had great experience with them in the past. I tried to pick the tech's brain on staff as to which route to go with the header (Ive been looking at JBA). He basically said there was no reason to get headers or a high flow cat, and even said most intakes are worthless, unless a turbo is going to be installed.
I come from an import tuner background where every mod is touted as necessary...i always thought if you did exhaust it'd be pointless without at least intake, and better yet that plus a high flow cat and headers... Has anyone done any or all these mods(I know tons of exhaust, much more curious about headers+cats)?
Am very interested as i have to fix my truck ASAP. Thank you + HAPPY NEW YEAR!

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