The engines can make good power as they were built during toyota's overbuilding/overengineering period in the 90s, but being a camry, the lack of aftermarket performance parts means you'll need almost everything custom fabbed, which means lots of $$$ if you don't have the tools to do it yourself. The custom front Y pipe on mine cost me 400 bucks as an example, but it did noticeably increase higher end power, not by a lot, but definitely enough to be noticeable by a butt dyno.
There are a few crazy camrys out there, apparently Tony the Tiger still has his frankensteined 1mz head-3mz block camry delivering 728 hp to the front wheels...needless to say, he's done a LOT of work to that car.
There is also an
air flow meter relocation mod you can do that is just moving the air flow meter closer to the throttle body and removing as many restrictions as possible, supposedly this increases throttle response and is the only intake mod that can actually do anything;
in theory it sounds good as the fuel pump is actually controlled by the AFM flap (set ignition to on, push the flap and you can hear the pump do its thing) however nobody else seems to have tried this and actually given a verdict. Once lockdown lifts where I'm at I intend to get the rest of the parts needed and make a post on this though. It's a pretty drastic mod however, as it involves drilling holes in your AFM, amongst other things.