[big_scoggs]

so do i have to run a aftermarket exhaust if im upgrading the downpipes..is it recomended? how many cats are in the whole exhaust system and were? sorry for the new questions kinda new to bmw's.

[domrep]

no you don't have to, some do and some don't. I upgraded my exhaust but not my downpipes...many do the opposite and many don't. Everyone has different reasons...for me I was willing to sacrifice the power to avoid excessive noise/smell from a full catless setup, if I do go with DP's I may go with catted.

4 cats total (2 on midpipe/exhaust and 2 on the stock down pipes).

[marv85]

I went with the catless DPs but left the stock exhaust (2 cats in midpipes) in place. The car sounds great but not excessive, and you can definitely feel the difference in power/responsiveness

[KyLu II]

The newb should had searched instead of asking

[big_scoggs]

the newb did search and when u search u come up with 5 million exhaust threads....

[ModBargains.com]

It honestly is up to personal preference. You can definitely do one or the other or even both. To be honest, you will most likely get more horsepower/torque gains with the downpipes alone than you would with an exhaust system. I would recommend that you check out the AR Design downpipes for the car and I'm sure that many more forum members can attest to the quality of this piece!

[r3v0]

catless DP in CA is a no no with smog too.
sad that the most performance gains are at the DP

[domrep]

Originally Posted by r3v0

catless DP in CA is a no no with smog too.
sad that the most performance gains are at the DP

catted dps is the answer and the happy medium. ~5-8hp you lose is negligble for most ppl...atleast for me it would be, and no one can feel that on the butt dyno.

[fisherbln]

Originally Posted by domrep

catted dps is the answer and the happy medium. ~5-8hp you lose is negligble for most ppl...atleast for me it would be, and no one can feel that on the butt dyno.

I'm going this route on my car. The only downside is the catted versions are ~$300 extra.

[DaFish]

Originally Posted by marv85

I went with the catless DPs but left the stock exhaust (2 cats in midpipes) in place. The car sounds great but not excessive, and you can definitely feel the difference in power/responsiveness

I did this, and I did a review. Search my posts and you will get a lot less hits.

Mike@n54tuning.com is a good guy to call and talk to as well. He hooked me up with my mods - AR catless DPs and stock exhaust. Way more power, no smell, bit more sound - LOTS more power and response. Not sure about passing emissions - could be 50/50 or find a "sympathetic" shop to do it.

[Syndicategt]

If you are a non-resident military living in CA, you can get a smog exemption form. If you are a resident in CA and your car is less than 6 model years old, you pay a smog abatement fee for 6 years before it has to be smog tested.

I went with catted DP's and a catless exhaust, so when it's time for me to smog, I just have to pop on my stock catted exhaust to pass

[DaFish]

Originally Posted by Syndicategt

If you are a non-resident military living in CA, you can get a smog exemption form. If you are a resident in CA and your car is less than 6 model years old, you pay a smog abatement fee for 6 years before it has to be smog tested.

I went with catted DP's and a catless exhaust, so when it's time for me to smog, I just have to pop on my stock catted exhaust to pass

right, I kept my DPs... $200 bucks to swap them out.... and then swap them back on... so $400 cost - I think every other year I have to do Drive clean in Ontario. I probably won't have the car past the first one....