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Discussion Starter · #1 ·
So this summer I'm planning on doing a custom straight pipe job. I've got a buddy with a WRX that did the same thing: pulled the muffler off and replaced with straight pipe. Seems like it pulls a little harder. I'm just wondering if I can expect to gain anything performance wise?
Edit: resonator and cats are staying on, so that I can pass emissions
 

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Humble E34 lover
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Only pre-conversion and a post conversion dyno runs can tell. However, I think the only thing you will gain will be decibels.

Steve
 

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Discussion Starter · #3 ·
I know it'll be louder. And it'll sound badass. I've heard an E34 M50 straight piped and it sounded great.
 

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i have straights on the M30 and i haven't noticed anything other than a great sound from the engine now :) i piped it because my old muffler was falling apart in pieces though.
 

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BMW CCA Memeber #445389
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I dont think youll have power gains. While our cars are pretty non restrictive in exhaust, you'll be doing the equivalent of removing a muffler. It'll sound nice though...
 

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I think it will sound good while accelerating but will it have that horrible rapping when you let off?
 

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not really. since you only take off the muffler you can hear it when you accelerate and when quiets down when not under load and if you let go of the gas it quiets down. yeah got get some noise but for the reason that you let go of the gas and only for that one second after or so.
 

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How about droning while cruising on the highway?
 

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on highway sounds like pure sex :jack: nice low but aggressive sound, then you hit the gas to pass and keeps the low sound profile but kicks it up a notch i love it :thumbup:
 

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Discussion Starter · #11 ·
I'm keeping the resonator on so there shouldn't be much if any rasp. It will be loudddd though. The one I've heard in person sounded like a v8 at idle but it was still a 525i
 

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Discussion Starter · #13 ·
I'm keeping the cat converter on so I'm not really worried about that
 

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u will not get big gains if you car is stock other than exhaust, maybe 1hp if u remove the cats. If you have something to complement it, like cams or bigger injectors and a tune, than yes you will get slightly noticeable gains other than just sound.
 

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I have a v8 car and the resinator has a small rust hole in it and is leaking a little bit. I was thinking about cutting the exhaust off after the cats and getting a chrome tipped muffler.
Bad idea? will this set engine codes or cause other issues like too much noise? I dont want it real loud, just to sound like a REAL v8.
 

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I have a v8 car and the resinator has a small rust hole in it and is leaking a little bit. I was thinking about cutting the exhaust off after the cats and getting a chrome tipped muffler.
Bad idea? will this set engine codes or cause other issues like too much noise? I dont want it real loud, just to sound like a REAL v8.
i actually did that to my 530, it sounded real nice, but when you let go of the pedal it rattles so i suggest two magnaflow cherry resonators before the tips. Makes it sound even deeper and no rattle.
 
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