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  1. #1
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    Cat-less DP's stink?

    Hello all, I'm new to the whole BMW thing, I've been playing with GTI's the last 15 years. Anyway, I had an 09 GTI before I purchased my BMW and had various downpipes on it. I loved the power gained with downpipes, but I couldn't stand the smell of the car when running without a cat. Does the N54 smell terrible, like the GTIs when pulling up to a stop, or does the odor not make it up to the front of the E90? I'm just curious. If some people notice that eye watering smell, I'll probably just get some catted downpipes or just leave the stock ones on. Actually, I doubt I'll leave it stock, but it's nice to think.

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    It happens with all cars when you delete cats.
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    I guess I'll just go for cats. For some reason American v8's tend to smell delicious at the track, but I'm pretty sure it's because they're running leaded fuel. Yum. -I'll probably end up with brain tumors from it.

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    do you plan on getting a catless exhaust?

    when i had stock exhaust and catless DP's, i couldnt smell anything. it was only after fully catless that it began to stink. I think you'll be ok if those are the only cats you plan on removing

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    Interesting there, Lost Marine. I thought about getting an aftermarket exhaust to get a little more sound out of the engine, but if I can get a little extra performance and noise with catless downpipes, while still maintaining the factory exhaust, I might go that route. That leaves me with some new questions now. Would I get better gains from A:catless downpipes and factory exhaust or B: stock downpipes with aftermarket exhaust with the secondary cat delete?
    Does the factory exhaust sound decent with catless downpipes? if so, this might be the way to go.

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    as for performance, there isnt much to be had with exhaust. there is some weight reduction, but actual HP, not much, 8 ithink is the average, whereas catless DP's can free up about 30 (also due to the ability to run more boost)

    when i went to DP's it only opened up the exhaust some slightly, and with a little rasp that i liked, no drone, not annoying, but just a bit more aggressive. When i went fully catless (exhaust) I chose a very quiet exhaust as well, so its a great benefit for me.

    I think catless dp's are just what your looking for unless your definatly set on exhaust, and definatly cant stand the stench

    but to answer your question directly, DP's provide much more power, smoother and earlier throttle response, exhaust just gives you a note

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    Well, I think that the catless pipes will be on my to-do list. I'll hang onto the stock exhaust and see what it's like. I'm probably going to do the downpipes soon after I'm able to get that jb4 jobbie. Thanks for the info, I appreciate the help!

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    smart choice with the JB4 as well, its gonna be the best of both worlds. Click here to enlarge

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    stock exhaust and cl dps is a winner for sound... High end exhaust's drone no matter what you read

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    Newbee question. If you lose the cats in your downpipes, is the car then still street legal?

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    David, your car will still have catayltic converters, just not as many as you had before. They're EPA laws that state it's unlawful to remove or defeat emisisons devices, but there is also the man-code which states that one must make a machine more powerful than the next guy. So in short, it's not legal, yet since you still have catalytic converters, you'll most likely pass a visual inspection if you ever need to. If the Mustang guys can do it, why can't we? Click here to enlarge

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    Click here to enlarge Originally Posted by Ryan Mills Click here to enlarge
    man-code which states that one must make a machine more powerful than the next guy
    well put! Click here to enlarge

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    Thanx Ryan.
    Al things being (more or less) equal, I want to win!Click here to enlarge
    But, where I live, in the Netherlands they don't do just a visual inspection. They analyse the exhaustgasses for emissions. So if half of the cats don't do a teriffic job, my car will fail the emissiontest and I will have to change the DPs and the piggyback before the checkup. In that case I think I'll pass on the DPs and just stay with the piggyback.

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    Click here to enlarge Originally Posted by DavidV Click here to enlarge
    Newbee question. If you lose the cats in your downpipes, is the car then still street legal?
    If you still have cats further back you should technically be able to squeak by.
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