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BMW 3-Series (E90 E92) Forum
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any one thought of gutting downpipes?
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05-04-2007, 10:15 PM | #1 |
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any one thought of gutting downpipes?
the b5 s4 guys do this a lot and it produces pretty good gains, comparable to aftermarket dps. Wondering if anyone has looked into doing this. I know nothing about the process of actually gutting it, just that the s4 guys do it.
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05-04-2007, 10:18 PM | #2 |
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dp? dps??
downpipes? diapers? you never know with the audi guys... ditch the abriviations, just type out the words already... unless you like seeing people ask "what is a dp" isnt it the pre-cats that they gut??? |
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05-04-2007, 10:22 PM | #3 |
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hes probably talking about gutting the cats out, ive heard of people doing this
but i think they are dumb, who wants shitty smelling gas and a back bumper with a nice soot stain on it? |
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05-04-2007, 10:48 PM | #4 |
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They probably think your an idiot. If you take the cats you can gain up to an extra 20-30whp and not only that but you can run c16 fuel and a map made for it and gain anywhere up to another 80-100whp, then your talkin about a 450-500whp 335i with god knows how much torque. Does that sound dumb to you?
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05-04-2007, 11:37 PM | #5 | |
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05-05-2007, 12:54 AM | #6 |
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05-05-2007, 12:55 AM | #7 | |
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I have ran no cat on my big turbo A4...have been through plenty of C16, 109, 103,100, and 91 octane..... and never once got a "nice soot stain". C16 on straight pipe will make your exhaust tips like a powder white, but then whipes right off. you might get a different smell, and i dont know about you but straight pipe, no cat and race gas is the BEST SMELL EVER!!! who would want 30-40hp and a "smell" of gas......shit sign me up. |
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05-05-2007, 01:17 AM | #8 |
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its not just that, its the simple fact that its highly illegal, and for a reason, the diffrence in pollutants is like the diffrence between the country dumping their oil into the nearest lake and recycling it.
its a shitty thing to do plain and simple. |
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05-05-2007, 01:45 AM | #10 |
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Its not a big deal in some states.
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05-05-2007, 07:39 AM | #12 | |
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Now, not having been under this car yet as mine is due to arrive in a week, I do not know for sure how many cats are on this vehicle. From what I have gathered there would be only one per bank so two in total and in parallel. So there is no pre-cat to gut. The only option would be to gut the main cats which I would take not suggest for a road going vehicle. Plus, the location of the cat for bank 1 would make it nearly impossible to gut. As such and if that extra power is needed, built downpipes would be a better option. |
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05-05-2007, 07:41 AM | #13 |
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05-05-2007, 11:07 AM | #14 |
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Drives: TiAg E92 335
Join Date: Oct 2006
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I had a serious cat-less soot stain on the rear of my s2k, I would wash the car and drive around the block and it would be back! I think that was more of a tuning issue with running too rich and the fact that the muffler was too close to the bumper though. The cat-less smell is really no big deal though IMO. Just slap a lot of wax on your rear bumper.
As far as gutting the cats goes, I think that I would just wait for an aftermarket downpipe to come out (I mean other then supersprint who makes some, but they are retardedly expensive). Another problem is going to be tricking the ECU into thinking that they are still on there. No one has been able to say if a simple mechanical o2 simulator would work for the 335.
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05-05-2007, 03:12 PM | #16 |
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05-05-2007, 03:16 PM | #17 | |
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05-05-2007, 03:23 PM | #18 |
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True it's hard to say, but dumping the cats and cleaning up the bends a little might make a big difference. The closer to the turbo, the higher flowing your exhaust needs to be! Let's just say I'm very optimistic a good downpipe will be worth around 15-20rwhp in a high boost car.
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05-05-2007, 03:29 PM | #19 | |
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However, I would love to see a catalytic converter pressure drop test to get an idea on the potential bottleneck of the stock cores. |
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05-05-2007, 03:31 PM | #20 |
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Yeah same here. Maybe everyone can ship in $10 and I'll gut my cats/dyno to see the difference?
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05-05-2007, 03:34 PM | #21 |
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05-05-2007, 04:15 PM | #22 | |
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hate to break it to you but state cars are doing it 50 tmes more than motor vehicles are! and im not trying to start an argument, its just the simple truth |
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