Exhaust noise and power anyone with this set up?

[Subaru addict]

Currently have std 172 2003 player with ktec stealth and cat. Car has blown between 87 and 90 dB on track days in last year.
I'm wondering about fitting 182 manifold. Ktec decat and ktec 182 style twin exit in bumper exhaust. The back box just cos I love the look of the twin pipes!
Does anyone else run this setup and if so does it show any power increase - ktec say upto 12bhp but I'm very skeptical! Also what about noise? Should this still pass noise tests?

 

[imprezaworks]

I love it when 'it could be up to 50bhp' and in reality 3. But covers themselves by the 'could be' part.

Same with broadband. Upto 8 million download, reality 15. Lol.