I've got a 1994 Euro C180 and the engine seems to be extra noisy as well as the exhaust. Last year, it got worse and I had to have the whole exhaust system replaced with originals except for the Cat which was too expensive for me, so I put in an aftermarket. Now the exhaust is still noisy, but better than before and still not as quiet as the 1998 C200. The old one had broken stuff inside of them and just had to be replaced. I feel that the engine is pumping out too much exhaust gases, thats why its so noisy in the back. Can someone come up with some adjustment somewhere to reduce this exhaust flow? Is it a tune up/down? Maybe the valves are jammed or need adjustment? In the front, the mechanical noises are a bit too loud, maybe this is normal for this engine being only a 4 cyl, but with twin cams and 16 valves all clapping together. Why is the C200 so quiet in idle and in acceleration? Maybe my timing chain is going? Maybe my pistons are going? Please help, thanks.

Next question is can I change to regular unleaded fuel because it is a few cents cheaper than the premium unleaded I am using now? How will this affect my car's performance and future running condition? Is it bad for the engine?