So I recently bought and installed the HKS Hi power muffler; not the silent, mine has the carbon tip and from what I’ve read there is a difference. So I had this thing installed along with a 2inch pipe going from the cat to this muffler that deletes the resonator and now it feels like I’m getting less power.

Is the pipe too big? Could something have come out wrong?
it sounds AMAZING by the way.

 

You probably lost a lot of torque across the range. Maybe a little more HP in the last 500rpm before redline.

 

I have the same carbon HKS Sport exhaust. I sure didn't lose any power.

HKS claims it's only about a 8hp gain to the wheels so you won't feel much of a difference at all just driving in traffic. But surely you didn't lose any HP bolting that on. As far as deleting your resonator goes. I have no idea if that is why you are losing power. Smaller engines do need back pressure for better vehicle performance though.