It's not a carb, it's an ITB setup but a bit more creatively assembled. Smog legality depends on your jurisdiction. It can add like 30-40 whp but you need a new programmable ECU like an AEM, Haltech, TEC III, etc. Hondata won't work.

The injection hardware will run you like $2300 plus another $1000 minimum for the ECU. No, it's not cheap.

I was answering the question of if you can get ITBs on a D-series, not if it's worth the money.