Have a 03 Sport Runner and I've been getting the p0420 and p0430 codes. I know every now and then before I clear the codes I'll get some 02 sensor codes but don't think it's the o2 Sensors. I'm thinking it's the cat because every time I step on it on the highway and I have the rear window open I'll get this huge smell of like fireworks or rotten eggs almost and those signs lead me to believe it's the cat. Well I was thinking of doing an exhaust set up and I was wondering if there was a tune for an exhaust and header set up for a 4Runner? One that'll increase my fuel mileage and of course the truck will run better because it'll breathe better. Any good exhaust set ups you guys know of and if they even have tunes for these suvs?

well for an exhaust, you have magnaflow or gibson. as far as i know, those are the only 2 exhaust available for our cars.

i had a P0420 code for my car and it went away when i replaced my Cat.

never heard of a tune for out 4runners that was available.

as far as the smell...even with a brand new 4runner, when you get on the throttle, it smells like rotten eggs. apparently toyota said it all depends on what gas station you use. when i had the P0420 code it smelled like rotten eggs, and after i put new cats on both sides and made the CEL go away it will still smell like rotten eggs when i get on the throttle.

Yep. I've learned I have to have the rear window up over like 35mph or I'll asphyxiate myself