My car has these symptoms (loss of power, different exhaust note, slight sputtering), directly after I did my headgasket. Now when I put the head back on I made sure cylinder 1 was at TDC, the crank lined up with its marks on the block, and the cams were set where I could slide in the cam plate I could also see the notch on the intermediate sprocket. The notch wasnt directly straight up though it was slightly more pointing towards the front of the motor. I guess my question is do these symptoms seem like it would be a timing issue? I have changed numerous sensors on the motor thinking those might be the problem. Thanks for any help Im running out of possible solutions!!