Hello all,
I am working on a friend's 08 Mazda 3 2.0L car that is loud as if there is a hole in the exhaust system. I have replaced the catalytic convertor and the sound persist. I used a statoscope to confirm that the sound is coming from the engine and not from the exhaust system.

Car doesn't accelerate well and I noticed that at a higher speed (20mph +) it seem like the car wants to slow down and the car shake. I thought it could be the VVT/ oil control valve, but all testing confirm that it is working properly.

Check engine codes;
U2064-FF Another control module requested warning indicator
B2212-0F Dim switch of panel is out of specifications
B2232-30 Circuit of front driver side air bag is open - Loop 2
P2188-FF too rich system at idle - bank 1

any suggestion on what can be causing the loud noise and poor acceleration? I figure the P2188 could cause the poor acceleration but that doesn't explain the loud noise.

thanks in advance... just wanting to get it fix.