Contour Enthusiasts Group Archives Forums Modifications Duratec Performance exhaust is smaller better

I've been reading and researching this site on and off since the day i bought my Mercury Mystique 2000.I,ve learned alot. My main question pertains to the length of the resonator and muffler either by Flowmaster or Magnaflow. The original part numbers for the magnaflow #10435 and #11225 -i notice are the favorite among the site. The 11225 being the oval o/c 4 x 9 measuring 20" nip to nip - 14" to body edge . The #10435 being the resonator 2.25 c/c 28" nip to nip - 22" to body edge and a 2.5 core.Now with these measurements in consideration im wondering is there a major factor i should worry about with going with a smaller inner core and/or shorter length. I want to switch the above mentioned with the Magnaflow stainless resonator part #14415 with a 2.5 core or #14445 which has a 2" core.Both are also shorter. The muffler by Magnaflow i was also considering is the #14362 4 x 9 oval body o/c 17" nip to nip - 11" to body edge. As for the Flow master muffler #942442 4" x 9.75 x 13 - 19" overall length. Can anyone help out with opinions and/or inform me on the differences ralating to the dimensions in core size, etc. One last thing, is the 2.25 in/out diameter accurate for the 2.5 V6.........not to much is it. 2.5 is too big , i believe there really is'nt any addition benefit.

I want to remember something I read somewhere about the smaller the muffler, the higher the pitch or resonant frequency of the exhaust note. Research helmholtz resonance and find how minute differences in diameter and length/width can make large differences (Look at an organ pipe).

Yea, there isn't much difference between 2.25 and 2.5 inch exhaust piping on a 2.5L. My car made 171whp the last time I was on the dyno and it probably wouldn't have been any different with the smaller piping. However, if you are going to step up to a 3L later, which I might, then 2.5in is better.

Well, something you need to consider in sizing an exhaust is where you're wanting to focus the powerband. The size of you're piping will have an effect on velocity and scavenging, smaller piping will create optimum velocity and scavenging at lower rpms, while becomeing restrictive up top, a larger exhaust won't produce good effect on the lowend, but will breath better up top. Too large will simple hurt power all around. Its the same concept as with the Duratecs intake design, we have two different runner to create the optimum velocity at a variety of RPMs. Usually when sizing and exhaust, its about finding a happy medium.

The difference between a 2.25 and a 2.5 is probably negligable on a mildly modified Duratec. The motor will absolutely love 2.5 inch better though, as its power, while broad, is focused in the upper rev ranges, especially the SVT.

why not get 2.5? I mean, its not like its hurting anything, and if you want to step up to say a 3L down the road it'll be better than having a 2.25"

hey you guys thank you with your imput...im goen all stainless with the 4" 2.5 core - 14"resonator item #14415 its shorter than the aluminized but i want longevity. The muff im sticking with same demisions just upgrading to stainless.if any one of you know the MagnaFlow resonator stainless part number that uses same measurments as the aluminzed # 10435 please inform me. Thanks again.

Well here i go again i go to purchase the upgrade to stainless and for some reason i had to check out MagnaFlows SS with tips 4" round Street Series. $93.65 for item #14809 - 63.61$ for SS universal 4" round resonator replacement #14415 - both/ = 157.26$ thats about a 30$ difference when you add up total cost from the orginal recommended resonator and muffler part #'s 11225 and 10435 each being $63.61 ( $127.22 )...or 25$ difference if u buy the SS universal muffler #14325 4x9 87.03$. Here's the site fulllineexhaust.com Any reason why no one has mentioned the Street Series? Im sure the majority of you are just plain switching over to the SVT exhaust system...but for those who dont want to spend the added cost of going full on with the Ford 3.0 exhaust - im thinking here's a set up only 30 bucks more. That by the way include tip or tips already. I've seen soo many of you buy the exhausts for 127.22$ and get high billet chromed out aftermarket tips that cost close to or over 30$. For 30 bucks more you get two full stainless muff's ; a bit more performance sound, tip and better quality. Any heads up on the SS Street Series? Is there something im missing? Other than cost options and Set up modifications? Alot of you already have the custom body kits and bolt on performance enhancments who could benefit. I really would like to hear from you all please. Me? well i dont have the body kit.