Quick question And trying to not to look stupid because I’m new to all this and my dads recently passed away and he was the mechanic teachin me things, I have a 2004 Monte Carlo ls and my dad and I were gonna build and restore it this winter, I’ve been looking at performance parts for it and doing a lot of reading on 3400s and was wondering what’d I’d have to do to put a bigger throttle body on it? Or what size to go with. I’ve seen some posts on it but still not to sure. I was looking at getting a 62mm but wanted some opinions on it first. Or what other upgrades I could do. Currently has a cai on it and muffler/res delete still has the stock cat but been reading about how it’s better to take the cat out and put a aftermarket one in because of the U Bend. Thanks in advance and sorry if I look dumb lol.

 

I'd suggest posting tech related stuff in the engine sub forum. You're more likely to get view traffic there that would be interested in reading/ responding to your specific topic (also makes it easier for others to search later).

I cant be of much help with that engine though. Do you know how big you can open the intake inlet up? No reason to have a TB bigger than the intake its flowing into.

 

Here is a thread with some ideas about some mods to help the 3400:
https://montecarloforum.com/forum/fw...p-power-46071/

But as far as the throttle body goes, there are options to put a bigger one on the 3400, but if you do that, I believe you are looking into upper/lower intake from a 3500, maybe even the heads. Unless you are doing those, consider half shafting the throttle body. Here's what I did with the throttle body in my 3400 Grand Am:
https://montecarloforum.com/forum/fw...hafting-56966/

I honestly feel you will want to explore a bunch of the mods in the thread I posted, you won't be disappointed. Items beyond those mods are possible, but you are then breaking into bigger territory (usually that it time to consider adding a turbo).