EVO intake and AWE exhaust

I'm ordering this next week, for installation by a local AWE installer in San Diego. If I eventually want Headers, does it hurt to do these two things first, or is there an order I need to pay attention to? TIA

NO you can do those and add headers later without a problem if you want, the AWE exhaust will bolt up to headers and the EVO intake doesn't have anything to do with adding headers or not.

Would this be a good time to ask the difference between headers and cats or how they affect each other?

Yes, an explanation would be nice to us novices....Thanx.

The car's primary catalytic converters are located on the headers. The awe catback gets rid of the second set of cat's located near the mufflers, these cat's aren't necessary.

The "headers" are an exhaust manifold that collects the exhaust gasses and sends them on down the rest of the exhaust system. A CAT or Catalytic Converter reduces pollutants to the level acceptable to a countries emissions laws. Porsche uses two pairs of cats, one attached to the header and one attached to the muffler. Since the secondary CATs are downstream from the O2 sensors, they probably DO remove more pollutants but removing them will NOT throw a code because they aren't part of the O2 loop. Now whether or not the car will pass a sniffer test is another question but most states, I think, have changed to just reading the OBDC codes to see if you have thrown any.

If "headers" are just an exhaust manifold that collects the exhaust gasses and sends them on down the rest of the exhaust system, then how changing them affect a raise in BHP?

By using thicker piping with less crimps and cats that flow more freely. Better headers provide a better and clearer path for the exhaust gasses. - Suneet

Correct. Normally, exhaust manifolds are not the best design. Good headers may have equal length tubes to ensure the gasses flow better

So AWE system is only CATS and no headers? Which producer (usually) more HP? Headers or CATs?

I think you are confused. You can buy headers with or without cats. Those without will produce 1-2 HP more than those with, but will fail emissions and require an O2 sensor to be turned off, so a trade off.

So which are preferred for more power? Cats first then headers or either one first.

Maybe a picture would help explain layout… below headers (FABSPEED) with 200 cell Cat’s. Also the sensor's need to connected to the header-Cat's as wiring lacks length to be modified to Cats on Cat back system. zornet :burnout:

So which producer more power? Catback (i.e AWE system) or headers (i.e milltek)? Better to combine catback from AWE with headers from Milltek (because AWE doesnt provide headers yet) or get full system (catback +headers) from Milltek? Should I start a new thread maybe? Dont wanna be robbin this thread.

Again, I would suggest you read the articles where I lay out the hp gains for headers with cats, (in 2 different forms) as well as 2 different cat back systems. The answer to every single question you ask is in those articles. I want you to read them. I also want to answer your question so here goes succinctly Milltek Headers alone - 8-10 HP gain Milltek Catback alone - 10-12 HP gain AWE catback alone - 10-11 HP gain Milltek Headers + Milltek Catback 20-22 HP gain Milltek Headers + AWE Catback 20-21 HP gain Virtually no difference between catbacks from AWE and Milltek, and catback gives slightly more HP gain than headers alone but the ranges touch so it will depend on your car, your dyno, your idiosynchracies, use these numbers as guideposts only. I would also encourage you to read the entire Milltek installation topic thread as well as the AWE one.

Don't worry about it, I'm learning more as you go along. I had some of the same questions

WD then check out this thread too: http://www.planet-9.com/showthread.php?p=111648#post111648 Very beneficial info!

Read it the other day, very informative. In fact, I copied all the relevant articles and will hand them to the mechanic when they install the exhaust and intake later this week. Where else can you get this kind of stuff..

They are necessary for emissions - especially in CA

fmarshall are you saying that the AWE exhaust will not pass California smog? If not, how do people deal with it? I assume you need to replace the original exhaust when it comes time to smog the car?

WD ... mind telling me where in San Diego you are having this done? I'm up in North County and would potentially be interested in the same mods - if you have a good report, that is (you can PM me...)

Does CA use a sniffer? If so, it might not pass. If not, and many states just read the OBDII for thrown codes, no worries.

CA used a sniffer back when I lived there. IIRC you had to do it to renew your tag.

Got her back yesterday, and it was an excellent experience. The shop did a great job, and the car sounds great! It makes a lot of noise when you get your foot in it, and has some resonance around 2K, but nothing worth whining about. As for the power, I have not yet had it tested, but it seems more powerful. I love the difference.

I'm in CA and had my 323i smog checked last weekend. They used a sniffer wand up the tail pipe and performed a visual inspection of the exhaust system. I assume they were checking for signs of tampering or aftermarket modifications.

just get straight pipes after the cat.