I’d recommend changing nothing on the engine, inlet or exhaust, unless you’re willing to do things properly and get it tuned to suit the mods.
The "need" for a tune depends on the modification and the starting point.
Cat-back exhaust mods arguably will have no effect.
Likewise, if more air can get to the airbox (eg due to the resonator being replaced with a second intake pipe), all the air is still flowing through the stock MAF housing and being measured.
Conversely, different exhaust manifolds, different MAF housings, different cams etc. have a more direct effect on things and usually require a tune.
Remember too that in the present case we are dealing with a stock naturally-aspirated "low powered" engine with a factory tune set to "very rich under load" for the international market Wally/safety factor. Simple low-impact mods are hardly going to cause skyrocketing cylinder pressures, lean conditions under load and/or destructive knock.
Different story making changes to an already-modified forced induction engine with cylinder pressures already close to mechanical limits. An adjustment to the tune to accompany more modifications is indeed good advice for something so highly strung.