I'm getting a rattle at 1900rpm (although typically around 1900rpm, it seems to be vibration dependent more so than rpm dependent), occasional rotten egg smell with hard accel., and seems like general loss of power most notable 1500-3500rpm.

Also, gas mileage has been mediocre for a little over a year, but terrible in the last 5 months or so, around 180-200miles per every 3/4ths tank of gas. MAF is less than 3yrs old. Spark plugs about the same. Premium 93oct gas. Mobil One full synthetic.

Haven't had a chance to get underneath the car yet b/c of a crazy work schedule and $h1tty weather.

Does this sound more like a bad/clogged cat. problem? Or maybe a damaged flex section? Or neither?

 

Because of the smell and bad MPG I'm guessing it's a cat problem.

Bad flex sections might rattle but you won't get that rotten egg smell.

 

The egg smell isn't real strong, but faintly noticeable. I'm wondering also if, besides the egg smell, a hole in the flex would cause similar symptoms.

 

Yeah with that bad mpg I dont think the flex would be causing that. So it would probably be the cat.

 

get obx headers and have a shop replace the cat with a pipe..problem solved

 

any emissions testing issues with that setup?

About how many hours should a shop be charging for a header and cat replacement?

 

No clue - here in MN we don't have emissions laws, I don't have a check engine light though.

Header install is a cake walk - people on here are girls about doing it themselves, you just have to have tools. The cat..honestly you can buy a test pipe instead of going custom.

A shop could do it in 5 hours maybe with any unexpected issues. It took me 6 with beer/breaks and I had to weld a new bung and grind a few things myself..otherwise it was easy.

 

OP did you do anything about this?