I was looking under the car and notice that there are 2 bulges along the exhaust, one bigger, the other slightly smaller. Both of them are located between the cat and the muffler. Anyone know the purpose of them?

 

I think they are called Air Silencers, or something like that. Sort of like a small muffler just to quieten things down a bit.

 

Are they hollow or there is something packed in them?

 

They are resonators. It has to do with the sound volume and frequency from the exhaust system.

Mark
www.Quantum-Racing.com