I had 2.5" turbo back with no muffler, only a cat, It was loud as ****, at low end till about 3000rpm it sounded like a big diesel truck, thenon the few occations I took it above 3000rpm it screamed, it just got louder and louder and louder, it was crazy.

 

On my old LST civic, I ran a 2.5" DP back to a 2.5" test pipe and a 2.5" mid section when I took it to the track and had the rear section for the street. On the dyno, removing the rear section gave me a 12% increase in power to ~250, with the exhaust completely on I would make ~225 hp. Leaving open DP, I would make a little over 260 hp.

 

MmmBoost? Im not challenging you at all. Not sure where u dreamed that up. I was merely saying with a turbocharger the size of the ko3(can barely get a finger in it) There isnt much backpressure there.