Contour Enthusiasts Group Archives Forums Modifications Duratec Performance To DemonSVT or anyone else Exhaust Question

Derk, I used a Bullet muffler in back that is supposed to only get loud at about 4000 rpm and it does just that. The intake seems to make noise at the same rpm so the two together sound nice. Inside the car is quiet till I punch it and then the sound is a little like a muted Mustang GT.

That sounds like a good setup. I had so much drone in the cabin (and yes, I had a middle muffler), and it was right at cruising speed. It drove me nuts. It was certainly not the way I wanted my SEDAN to sound. BTW, you got a good deal on all your exhaust work.

Thanks, I'll be honest Demonsvt had me feeling like a moron so I took the Contour out and reved it up. It sounds nice, performs great and makes zero drone at highway speed. I guess I lucked out. BTW I was so pissed at myself after reading Demon's reply that I challeged an Acura rsx type-s at a stop light. I had him by half a car lengh at 100 miles per hour when he gave up.Not bad but I'm a pretty fast shifter.

Way to go streetracer.

I actually went the other way and got the y-pipe before the catback which does seem to have improved performance.

Yes, your car does have a y-pipe, but no, it isn't as good as some available aftermarket pieces. Keep in mind your car had an exhaust previously but it wasn't as good as your aftermarket exhaust.

Have fun with your M3.

Well, why not just go back to the same shop and have them optimizy your stock Y? Should be good for another 4 hp.

How To and pictures in the mods section.

Originally posted by Frankiehotdog:

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Also, that a good crush bent can be better than a poor mandrel bend if the mandrel bend is welded anything but perfectly flush and without any holes in the weld

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Bull sh^t! That makes it sound like you do not even understand what you are talking about.

No matter how "gently" you crush a pipe. It's crushed none the less.

2.5" pipe crush bent to 90 degrees has an inner diameter are 2.05-2.1"

The same pipe mandrel bent only necks down to around 2.4"

That's an unbelievable amount of difference. There there comes the fact that that every decrease and subsequent increase in diameter robs exhaust energy and slows velocity. Major lose/lose situation.

I really suggest doing a search on crush/mandrel bends! This is just a quick explanation.

Originally posted by Derk2000:

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performance problems? well, the first time I dynod I only pulled 165. I was a little sad, yes.
Otherwise, if you're just looking for an improvement over the stock straw-for-an-exhaust-pipe, a 2.5" crush bent system should certainly net you some hp gains. If you're looking for the best flowing system, mandrel bends are a MUST!

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Actually I'm willing to bet any crush bent system will not outperform the stock SVT exhaust (which is mandrel bent BTW) with the resonator removed or probably even with it just replaced with a quality unit!

...and yeah 165 is about what a bone stock SVT pulls. (165-168 range) Glad to see it's "perked" up now with a proper exhaust.

Originally posted by DemonSVT:

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Originally posted by Derk2000:

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performance problems? well, the first time I dynod I only pulled 165. I was a little sad, yes.
Otherwise, if you're just looking for an improvement over the stock straw-for-an-exhaust-pipe, a 2.5" crush bent system should certainly net you some hp gains. If you're looking for the best flowing system, mandrel bends are a MUST!

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Actually I'm willing to bet any crush bent system will not outperform the stock SVT exhaust (which is mandrel bent BTW) with the resonator removed or probably even with it just replaced with a quality unit!

...and yeah 165 is about what a bone stock SVT pulls. (165-168 range) Glad to see it's "perked" up now with a proper exhaust.

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I wonder how a crush 2.5" would compare against a SVT exhaust. That'd be interesting info.
165 wasn't quite bone stock (I had the MSDS headers on the car), but I am certainly glad it's "perked" up as well.

I don't mean to play devil's advocate but here is a dyno graph of our 2 1/2" "smooth" crush bent system versus a resonatorless stock SVT exhaust system. This was the before and after runs with our SVT, when owned by a previous customer. The only changes between these runs was the exhaust system.



....and here is our SE, before and after the install of our non mandrel bent custom exhaust. Please note the maximum torque is a bit deceiving because the operator, on run 12, started the run at a higher rpm, which missed out on the max torque which occured at a lower rpm than the start point.

DemonSVT, how due you explain cawong11's results. Like i've always stated I am not an expert but I can feel a significant difference in performance. Considering I sought your advice, I found your last comment insulting. I am a newbie to mods but why do you find it necessary to point fingers at me to say I don't know what I'm talking about. I'm hear for advice and not to be insulted. Thank you cawong11 for your input which clearly showed a 2.5" crush bend improving performance on a stock svt exhaust.