I have the Plazmaman kit and in my opinion it's definitely worth it as I specifically wanted more induction noise (and hectik dose bro). I'm not an expert but I assume there would be a small (5kw~?) gain. No need to get a tune, and this was the first mod I did (plus intercooler piping), but it sounds 1000x better after I upgraded intercooler and exhaust + tune etc.
Antz kit looks alright for the price but I'm glad I went with Plazmaman.