My Accent is coming along nicely. Recently I was contemplating i's future, and a scary thought came up. I have a cat back exhaust on it along with a custom CAI. When I had the exhaust installed, they had to remove one of my resonators. I was wondering if these mods would make my car fail emissions, or how big of a difference they would make between stock and post-modifcation emissions. I was thinking about adding a header and a trottle body next year, would this be a huge factor also? I'm going to college this fall, and if it doesn't pass emissions while I'm away, there's no telling what my folks would have ripped off of it and how much $$$ I would lose. Thanks.

 

If it had a caton it and I'm sure it did make sure to have at least another cat back on it. If it had 2 I'd put 2 back on it. You can all ways buy high flow units that wont hurt performance that much if any.

Also make sure if a cat had a O2 sensor before a cat and after a cat put them in the same spot or your ECM might not like it.

 

You said they removed a resonator, and put a catback on--so the headers and cat are still in the stock arrangement? This will have almost no affect on the emissions. The emission control device on the exhaust is the cat, and since it is untouched it would still function as before, right? Noise is the primary pollution created. wink

Intake manifold and throttle body upgrades wouldn't have much effect on emissions either. The majority of the compounds they check for in emissions test are created in the combustion chamber, the intake manifold is upstream of this. So long as you are not getting so much air in that you are running way lean, or so much fuel that your are too rich, this won't hurt you.

Longer duration or higher lift cams will increase your emissions. How much really depends on the cam you are using, your timing, your fuel ratio, and a few other factors.

 

Thans a lot, that will really help me sleep better. Next season, when I do put a header on it, can I put the cat anywhere after it. I noticed the ones from SR don't have a cat mounted right on the header, like the stock one. Is this easy to change or not?