Yea my 03 4runner smelled like rotten egg/sulfur smell upon acceleration.

I heard a rattle in resonator and lil leak on a rusted flange. Heard some rattling in resonator if i tapped on it.

Replaced that with Magnaflow overland catback.


Turned out the pass header was cracked and leaking. They said the inside of the cat got clogged or broke apart (hence rattling and smell). Meineke wanted to charge me $3000 for manifold and y pipe (I think OEM as well).

all my bolts and flanges were so rusted. it was cheaper for me to just replace both headers, y-pipe at same time from on Rockauto and just threw in 4 new Denso O2 sensors from there as well.

This was like 2 weeks ago. I dont know if its an issue with the header but sounds like the metal expanding and contracting. Makes a ticking sound now on driver side header area when I drive and for a min after i shut the truck off. Hopefully this goes away. Driving me insane.

Also there are 4 cats. 2 built into manifold and 2 on y pipe.
The y pipe flanges were so bad, i just decided to replace it all to not run into issues later.

Here a run down on what I ordered and brought it to Meineke: (not the best or the worst parts from Rockauto - I usually get the favorite ones on the site)

2003 TOYOTA 4RUNNER 4.0L V6
AP / EASTERN 641349 (40599) Catalytic Converter $ 287.79
AP / EASTERN 641524 (40598) Catalytic Converter $ 299.79
AP / EASTERN 642191 Catalytic Converter $ 293.79
AP / EASTERN 642192 Catalytic Converter $ 323.99
DENSO 2344804 (234-4804) Oxygen (O2) Sensor $ 44.99
DENSO 2344805 (234-4805) Oxygen (O2) Sensor $ 45.79
DENSO 2349047 (234-9047) Oxygen (O2) Sensor $ 112.89 x 2 = $ 225.78
Shipping Ground $ 52.97
Tax $ 104.34
Order Total $ 1679.23

Install for above around $350 at Meineke


Magnaflow overland catback - $720 + sh/ tax (I believe you can get a stock rockauto one for around $150-180?)
$100 install

Total for everything ~$2500 (and it still doesnt sound right but the egg smell is gone)


Good luck with whatever you decide. I was almost tempted to sell it. Still might. Hit me up if you have any questions.