I got my 2011 Toyota Axio (Corolla) serviced. After the service when starting, the car sounds like loud a bit like the exhaust sound of a rally car.

I went back to the service mechanic. He looked at it and said there is a pipe underneath the vehicle; the Silencer is missing. He said I can get it welded and it will be just fine.

The next two mechanics I went for opinion said that the Catalytic Converter is stolen by hearing the sound of the car when starting. They suggested that the Service Mechanic could have removed the Catalytic Converter.

I went to a third car garage. Upon inspection by raising the car they said that it was all fine. The Silencer or Muffler was there and the Catalytic Converter was also present.

I went to a fourth place, Exhaust Specialists. Upon raising the car, they said the Catalytic Converter and Silencer where present. They said that the pipe needed replacement, with seal gasket and rear assembly. Instead of doing that, I got the pipe welded by them as it has some cracks and left with the quotation.

Symptoms: When pressing gas or driving, there is muddy or greeny water coming out of tail pipe (FYI it has been raining heavily on and off in my area and I have had to at times drive over swamps and flooded waters before and after the Service). Also, the car when starting sounds a bit like rally car exhaust. I am monitoring fuel consumption which could be tad on the higher side but that remains to be seen. There is a bit of vibration in car when starting. There is no Engine light.

I am wondering why problems started after my car service. Before, everything was fine. Different people are giving me different stories.

Is there anything that cannot be rectified? Is it serious issue? What is actually the problem with my car? Should I get rid of the car.

I am a Corolla fan. My previous car was a used Corolla also and I used it for 11 years with cheap maintenance and good gas mileage. It was a work house and had no issues whatsoever. I regret I sold it.

Please help!