On an older car, you should, as the tired, old tech intake being replaced by a brand new tech intake. but don't waste your money on a CAI as it's pointless on a turbo setup. you should be able to easily fit one with how many designs they have out now. i remember reading how people took eclipse CAI and fitted them to their galants just fine.
"I've heard that turbo cars usually get better gains out of intake/exhaust mods than NA cars... is that true?"
Well turbos compress the air as it comes in (intake) and is powered by the gases exiting (exhaust) so yes
