Based in New York. Sounds much better. Grammatically correct. If you want to use "base in" you'd have to go for a different structure. With A base in NY. But this changes the meaning. It has ONE base in NY and bases in other places too.

Hi! To my ear, ´´based in New York`` sounds better.

Is it better to put "... said THE results are very..." ?? (Without "that") is it more common and sound natural???