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      12-03-2007, 01:25 PM   #1
karmasabish
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Typical HP / Performance improvements with Exhaust on MCoupe or MRoadster

what kind of performance improvements are we seeing in general on the MCoupe/ MRoadster?

what in everyone's research has been the system with the best gains?
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      12-03-2007, 07:03 PM   #2
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18 views and no one knows? wow
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      12-03-2007, 07:55 PM   #3
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Well, as you're soliciting opinions - I don't think many of them are worth a damn, in terms of bang for buck. You can do chips, headers/exhaust, intakes, and get small increments of power after spending thousands, but if you're craving more power just go ahead and get a supercharger (or more sensibly save up and trade for something with a turbo, like the Porsche 996TT).

Then there's the old quote: you don't hire a porn star with a 10 penis to film him jerking off. What, exactly, do you need all this power for, Mr. Jeremy? Most people serious about performance don't ask about more horsepower, they're looking for better brakes, stickier tires and a taut yet supple suspension, and are maybe looking at lightening the car.
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      12-03-2007, 08:29 PM   #4
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Quote:
Originally Posted by epbrown View Post
Well, as you're soliciting opinions - I don't think many of them are worth a damn, in terms of bang for buck. You can do chips, headers/exhaust, intakes, and get small increments of power after spending thousands, but if you're craving more power just go ahead and get a supercharger (or more sensibly save up and trade for something with a turbo, like the Porsche 996TT).
Then there's the old quote: you don't hire a porn star with a 10 penis to film him jerking off. What, exactly, do you need all this power for, Mr. Jeremy? Most people serious about performance don't ask about more horsepower, they're looking for better brakes, stickier tires and a taut yet supple suspension, and are maybe looking at lightening the car.
My sentiments exactly. Aftermarket exhaust systems typically do nothing to increase horsepower unless the catalytic converter(s) are removed. The only advantage to be gained from most aftermarket exhaust systems is a slight reduction in weight and a sound that makes you think you have more horsepower. And of course your wallet is lighter which may result in a better horsepower to weight ratio
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      12-03-2007, 09:18 PM   #5
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http://www.remusexhaustshop.com/road...04r-p-535.html
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      12-04-2007, 06:19 PM   #6
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Originally Posted by Remus View Post
not too shabby! thanks for this.
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      12-04-2007, 06:24 PM   #7
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Quote:
Originally Posted by jmillet View Post
My sentiments exactly. Aftermarket exhaust systems typically do nothing to increase horsepower unless the catalytic converter(s) are removed. The only advantage to be gained from most aftermarket exhaust systems is a slight reduction in weight and a sound that makes you think you have more horsepower. And of course your wallet is lighter which may result in a better horsepower to weight ratio
i should have clarified, i know what exhaust systems can do in general, what i'm wondering is closer to:

"well the remus system has shown a gain of 9 peak hp, but not much over the powerband

Supersprint has a good improvement in mid-range performance but generally only a 6 HP improvement in peak."

i dunno, something quantifiable by those who have experience purchasing and modding the z4 M Roadster.


thanks for the help
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      12-04-2007, 07:03 PM   #8
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Here's the thing...You can't just bolt on an exhaust and watch the HP grow 30 to 40 points. Moding the exhaust is supposed to help the engine get rid of waste gases and improve performance. However, our brilliant German engineers has added "safety" features to our ECUs and if the flow increased too much it cuts power and you actually lose performance. So tuning the exhaust should also come with ECU optimization.
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      12-04-2007, 08:35 PM   #9
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Quote:
Originally Posted by karmasabish View Post
i should have clarified, i know what exhaust systems can do in general...
I should clarify - I didn't think you didn't know what they do. I was simply saying the bang for the buck is too weak, even with today's buck. Noticing an extra 6 or 9 horsepower is literally like saying that you've got 330 Clydesdales pulling the Budweiser truck and you suddenly rein up and yell "Hey, you two horses there - stop slacking off! I can tell!" If you need a dyno and the day's humidity report to tell you where you spent 2 grand, you wasted 2 grand.

Two grand spent on a 3.91 diff or a coilover suspension would be money better spent, imo, with immediate, clear performance differences that any $10 stopwatch could measure.

"Intakes, chips, exhausts - the true speed Jedi craves not these things."
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      12-05-2007, 04:55 AM   #10
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If you think an exhaust system bolt on is going to result in huge power gains out of a inline 6 3.2 litre engine that revs to 8000 rpm I'm afraid to be the bearer of bad news, but your going to be sadly disappointed.

The engine is highly strung in stock form, the only cars that make good gains from after market exhausts are either V8's or cars with FI.

You would be MUCH better from a performance perspective buying a set of 4.10 gears (3.91's are still too long with 6 cogs)

Although the stock exhaust system on the M Coupe doesn't sound as good as the one on the E46 M3, and I'm sure like it there would be a considerable weight saving advantage as well. Remus make good, high quality systems that have a reputable name at an accessible price, I would defiantly consider them the first port of call for an after market system for an M Coupe.
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      12-05-2007, 01:37 PM   #11
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Quote:
Originally Posted by epbrown View Post
I should clarify - I didn't think you didn't know what they do. I was simply saying the bang for the buck is too weak, even with today's buck. Noticing an extra 6 or 9 horsepower is literally like saying that you've got 330 Clydesdales pulling the Budweiser truck and you suddenly rein up and yell "Hey, you two horses there - stop slacking off! I can tell!" If you need a dyno and the day's humidity report to tell you where you spent 2 grand, you wasted 2 grand.

Two grand spent on a 3.91 diff or a coilover suspension would be money better spent, imo, with immediate, clear performance differences that any $10 stopwatch could measure.

"Intakes, chips, exhausts - the true speed Jedi craves not these things."
lol @ Stop slacking off, i can tell!

its a bummer that is so tough to get more power out of the old girl. sigh...
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      12-06-2007, 10:57 AM   #12
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Quote:
Originally Posted by karmasabish View Post
i should have clarified, i know what exhaust systems can do in general, what i'm wondering is closer to:

"well the remus system has shown a gain of 9 peak hp, but not much over the powerband

Supersprint has a good improvement in mid-range performance but generally only a 6 HP improvement in peak."

i dunno, something quantifiable by those who have experience purchasing and modding the z4 M Roadster.


thanks for the help
In real world performance, you would be better shedding 10 lbs than adding 10hp.
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      12-08-2007, 10:08 AM   #13
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Let's put a 9 hp increase in perspective - it amounts to 2.7%. It has been written often that the minimum hp increase that can be felt by the driver is 10%. So you would need 3 or 4 improvements like this to notice them.

Better off tackling weight...
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      12-10-2007, 08:17 PM   #14
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As has been said before, power to weight ratio is key in a N/A car. Exhausts for N/A cars should be bought with weight savings in mind rather than overall HP increase.
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      12-11-2007, 12:37 PM   #15
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BTW for those interested we'll have this exhaust back in stock in 1 week:
http://www.remusexhaustshop.com/seri...8td-p-534.html
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      05-08-2008, 05:40 PM   #16
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as i have read somewhere b4 that the M3 exhaust is very similar to the Z4 M's

i think the M's is a bit more restrictive due to the smaller fit (hence the 3hp less than the 333hp M3)

and i have also read that the M3's stock exhaust is tuned out to very close to the max (meaning an aftermarket exhaust doesnt do much except louder and lighter....but not a whole lot of real hp/tq gain)

so with that in mind i would guess that doing an aftermarket exhuast on the Z4M will not result in a sig gain.....at least not for the $$ that you will pay for an exhaust

and yes i agree with the previous comment re: the CAT is the 'issue' here any mod BEHIND the cat in these cars are not gonna make a big diff
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      05-08-2008, 08:52 PM   #17
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Exhaust is for sound and weight savings in most cases.
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      05-09-2008, 07:36 AM   #18
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Quote:
Originally Posted by Rom3n View Post
Exhaust is for sound and weight savings in most cases.
i never realized people bought exhausts expecting significant performance gains.
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      05-09-2008, 08:46 AM   #19
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Quote:
Originally Posted by Rom3n View Post
Exhaust is for sound and weight savings in most cases.
+1

But my current muffler bypass system gave me ALOT of high end power. Maybe 5-10 hp It kicks in around 5k rpm and feels like the car is supercharged

But such a loss in low end torque
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      05-09-2008, 08:52 AM   #20
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Quote:
Originally Posted by MMMazing07 View Post
+1

But my current muffler bypass system gave me ALOT of high end power. Maybe 5-10 hp It kicks in around 5k rpm and feels like the car is supercharged

But such a loss in low end torque
Come to think of it my exhaust makes my car feel supercharged also
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      05-09-2008, 09:26 AM   #21
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Quote:
Originally Posted by Rom3n View Post
Come to think of it my exhaust makes my car feel supercharged also
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      05-09-2008, 11:30 AM   #22
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Quote:
Originally Posted by Rom3n View Post
Come to think of it my exhaust makes my car feel supercharged also
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