If I were to get ported exhaust manifolds, a new downpipe as well as the cat-back system I told you about.....what, if anything would I need to change as far as the engine? Throttle body, upper and/or lower intake? Or can I just go and put the fenderwell intake right on without changing anything?

This is for my 2005 Monte Carlo LS with the 3.4.

 

You don't have to do any intake side mods when doing exhaust side mods. Certainly they can complement each other, but its not mandatory. A retune of the pcm would be best after doing all of those mods so it isn't having to correct itself via trims for the change in airflow.

Not to be a downer in every thread like this, but Id really reconsider before dropping that kind of money on it. You've probably got $2k worth of mods thatll probably struggle to add 20 crank hp combined across all of them. Just saying the bang for the buck with that type of stuff is very low.

 

I would not touch the exhaust manifolds.. Youll lose power. I lost power switching to headers on a supercharged engine.

 

I agree with bumpin, a lot of the stuff mentioned is a lot of cost with low return.
Some N-body 3400 guys will top swap heads, upper/lower intake from a 3500. They are check to get, betting flow. You still have to address mounting the coils and throttle body.

Another option, look at this write up on some cheap mods. Not huge power gainers, but fun and cheap.
https://montecarloforum.com/forum/fw...p-power-46071/

For example, I daily drive a 2004 Grand Am with the same 3400. No resonator, L67 coils, half shafted the throttle body, did a coolant bypass (so coolant does not flow through the throttle body) and a better water pump. I also made some minor tweaks to the PCM for improved transmission shifting. All cheap and was fun to do.