Manual have more better gear ratio some comes with LSD. Auto b16a have milder camshaft and lower rpm gear change. U can use manual cam or type r cam and piston with ur auto b16a for better acceleration but performance still cant compare to a stock b16a manual.
I suggest if u wanna keep auto just change to b20b/b20z block with some bolt on mod. If u want power and reliable then go for b16b or b18cr halfcut comfirm puas!
Just acquired an Airtrek Turbo over the last few days, and has been quite an experience. There have been a few mods done to it by previous owner, and has been great.