The car is a 99 ex. I've been running a DC 4-2-1 and Apex WS2 for a few years now. A couple of months ago I started noticing a rattling sound (rocks in a can) that I thought was coming from my exhaust. I figured it had to be the cat since it had almost 200k on it. I went with the skunk2 test pipe and blox cel elim. The only problem is the top of the o2 sensor is now up against the bottom of the car and making a vibrating noise itself and the other rattling noise is still there too. i got a hammer and tried to make some extra room but the metal didnt give too much. Any ideas on how to make some more room for the 02 or what the noise might be?

 

heat it up with a torch then use a bigger hammer

 

buy an o2 bung $5, weld it onto the test pipe in a different location,repositon the o2 sensor

 

the rattling mite be a vacum in the exhaust. if your running a stock exaust that would make sounds. you need the exhaust the flow more open and freely