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Will free flow mufflers increase hp?


CR2013GT500

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IMO the stock mufflers on these cars are free flowing - it's the cats that need to go. I can't see Ford putting restrictive mufflers on this car when they are bound by other bottle necks for emission purposes and are trying to get max power. People seem to change them more for the sound I think. I kept mine, but put the off road H-pipe on- big difference.

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IMO the stock mufflers on these cars are free flowing - it's the cats that need to go. I can't see Ford putting restrictive mufflers on this car when they are bound by other bottle necks for emission purposes and are trying to get max power. People seem to change them more for the sound I think. I kept mine, but put the off road H-pipe on- big difference.

So you noticed more HP with the H pipe? I thought that just equalized the pressure between the two & changed the sound to a deeper tone.

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IMO the stock mufflers on these cars are free flowing - it's the cats that need to go. I can't see Ford putting restrictive mufflers on this car when they are bound by other bottle necks for emission purposes and are trying to get max power. People seem to change them more for the sound I think. I kept mine, but put the off road H-pipe on- big difference.

I agree if you still have stock manifolds and cats but I have neither. I have headers with off road. The factory mufflers flow good but looking inside they do appear to take a somewhat dirty path. Would like to see a dyno sheet before and after on a 700+ hp engine.

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So you noticed more HP with the H pipe? I thought that just equalized the pressure between the two & changed the sound to a deeper tone.

The H pipe gives you more low end torque whereas the X pipe gives more power in the high rpm range.

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Headers I have always believed in. I would, however, like to see some flow data comparing stock manifolds, shorty and long tubes on this motor. Headers on these motors seem to be in the Pain in the Ass category as far as install and day to day running - heat problems, etc... Your thoughts pls.

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Others have done this in the past. Use SEARCH.

Tried search but did not find anything. Maybe you can post a link?

Headers I have always believed in. I would, however, like to see some flow data comparing stock manifolds, shorty and long tubes on this motor. Headers on these motors seem to be in the Pain in the Ass category as far as install and day to day running - heat problems, etc... Your thoughts pls.

My headers are perfect for day to day. Not sure what you mean however. Don't notice any heat problems. Engine runs very cool with headers and with my 170* tstat even in 90* ambient temps.

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Tried search but did not find anything. Maybe you can post a link?

My headers are perfect for day to day. Not sure what you mean however. Don't notice any heat problems. Engine runs very cool with headers and with my 170* tstat even in 90* ambient temps.

Sorry, I don't have time but know it's been discussed ad nauseum here and in other forums, same for headers. Gains are minimal from exhaust. If you want HP change the pulley/tune. If you want sound, change headers and exhaust. If you don't have time to do the research then put mufflers on and you'll probably get 100hp more. NOT. But almost anything will sound better.

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Sorry, I don't have time but know it's been discussed ad nauseum here and in other forums, same for headers. Gains are minimal from exhaust. If you want HP change the pulley/tune. If you want sound, change headers and exhaust. If you don't have time to do the research then put mufflers on and you'll probably get 100hp more. NOT. But almost anything will sound better.

I'm sure it's been discussed many times for cars making less than 700 hp. Just not finding any info on 700+ with free flow mufflers vs. stock.

 

Already have a pulley and tune and more. Actually sounds pretty good with stock mufflers with my American Racing headers and off road pipe.

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Tried search but did not find anything. Maybe you can post a link?

My headers are perfect for day to day. Not sure what you mean however. Don't notice any heat problems. Engine runs very cool with headers and with my 170* tstat even in 90* ambient temps.

Yah sorry, I should have been more specific. By heat I meant the surroundings around the headers with stuff getting too hot because they are now way closer to the heat than when it was just manifolds. Did you have to change the motor mounts for clearance?

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Yah sorry, I should have been more specific. By heat I meant the surroundings around the headers with stuff getting too hot because they are now way closer to the heat than when it was just manifolds. Did you have to change the motor mounts for clearance?

I don't believe the heat from my headers is doing damage to any other wires or parts. Going by memory I don't have any wires or anything that I feel was too close that damage could occur. I did not install the headers myself but I did check it over and did not see any problem areas.

 

I'm running factory motor mounts.

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I'm sure it's been discussed many times for cars making less than 700 hp. Just not finding any info on 700+ with free flow mufflers vs. stock.

 

Already have a pulley and tune and more. Actually sounds pretty good with stock mufflers with my American Racing headers and off road pipe.

 

......if you already have headers and no cats, be careful with going with a muffler that is too wide open. I had corsas initially and they were way too loud. I went with the borla touring mufflers; with a no cat system, and I do not have headers....love the sound. You really are not gonna see more than a couple hp variance with the mufflers. Most of the real restriction is up front. I have been following this stuff since 07 I just don't remember anyone going to the trouble of doing a before and after dyno on just a muffler swap. Just go for a sound you enjoy.

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......if you already have headers and no cats, be careful with going with a muffler that is too wide open. I had corsas initially and they were way too loud. I went with the borla touring mufflers; with a no cat system, and I do not have headers....love the sound. You really are not gonna see more than a couple hp variance with the mufflers. Most of the real restriction is up front. I have been following this stuff since 07 I just don't remember anyone going to the trouble of doing a before and after dyno on just a muffler swap. Just go for a sound you enjoy.

Too much noise would definitely be a concern. Reason why I went with stock. But I have heard good things about Kooks mufflers for our cars.

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to answer in simple terms, on a stock GT500 the cats are most restrictive, followed by the mufflers. changing either will change the sound. the debate over cross-pipe style (X or H) is mostly a waste of time. they influence the sound and flow by a negligible amount. the stock manifolds are decent, with only minimal gains with shorties in terms of heat and weight. long-tubes are better for flow but not really necessary on forced induction cars and come with added noise and emissions complications. long-tubes require a new ECU tune. no other exhaust mod does.

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If you have long tubes and an o/r mid pipe you've eliminated most of the restriction in the exhaust. Changing mufflers will mainly effect the sound, with the headers and o/r mid pipe you will need to be careful w/ muffler choice most tend to stick w/ the stock mufflers w/ that set up and are very happy. I personally run ARH 1 7/8 headers hi flow catted H and Supersnake mufflers on my 14 and couldn't be happier w/ the sound.

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Ok, so we have all come together with our views on this subject so let's push it a little further. Get out your tech savvy and your search engines for this one. Given you have opened your bottle necks on the intake side with say a JLT and bigger throttle body, and installed either an off road H or X pipe, or a high flow cat setup, at what RPM do headers out flow the stock manifolds? The stock manifolds look pretty good and I suspect headers only improve flow at a very high RPM.

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Ok, so we have all come together with our views on this subject so let's push it a little further. Get out your tech savvy and your search engines for this one. Given you have opened your bottle necks on the intake side with say a JLT and bigger throttle body, and installed either an off road H or X pipe, or a high flow cat setup, at what RPM do headers out flow the stock manifolds? The stock manifolds look pretty good and I suspect headers only improve flow at a very high RPM.

....at lower power/supercharger pressure levels, I would not bother with headers, since they cost a bit and are a pain to install. 20-30 hp at best until you have fully modified an engine. I am at 700 hp and torque to the rear wheels with more or less basic stuff (TVS 10% lower etc) without headers. Money would be better spent on other things IMHO.

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....at lower power/supercharger pressure levels, I would not bother with headers, since they cost a bit and are a pain to install. 20-30 hp at best until you have fully modified an engine. I am at 700 hp and torque to the rear wheels with more or less basic stuff (TVS 10% lower etc) without headers. Money would be better spent on other things IMHO.

Curious as to where you got the 20-30 hp from headers? Do you have actual dyno sheets before and after on a 700+ hp engine?

 

With your current 700 rwhp would be interesting to see what headers would do for you. Can you post your dyno sheet? Would like to compare it to mine.

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....at lower power/supercharger pressure levels, I would not bother with headers, since they cost a bit and are a pain to install. 20-30 hp at best until you have fully modified an engine. I am at 700 hp and torque to the rear wheels with more or less basic stuff (TVS 10% lower etc) without headers. Money would be better spent on other things IMHO.

Yah like traction. lol. I think that's where I'm going to focus my attention now. 1st and 2nd are almost useless because I can't put my foot into it without incinerating the tires! I think if you step back and look at what SVT did with these cars it's absolutely outstanding. They gave us a race car, that meets emissions, but they made it very easy, and cheap, to give us another 200 hp and 200 pound feet or so above stock without alot of messing around. I did all my mods within a day - a short day and for about $4000.00 CAD. No other car out there can say this. Corvette, Camaro, hellcat, Viper, nothing even compares to the HP per dollar you can get. Cheers!

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Yah like traction. lol. I think that's where I'm going to focus my attention now. 1st and 2nd are almost useless because I can't put my foot into it without incinerating the tires! I think if you step back and look at what SVT did with these cars it's absolutely outstanding. They gave us a race car, that meets emissions, but they made it very easy, and cheap, to give us another 200 hp and 200 pound feet or so above stock without alot of messing around. I did all my mods within a day - a short day and for about $4000.00 CAD. No other car out there can say this. Corvette, Camaro, hellcat, Viper, nothing even compares to the HP per dollar you can get. Cheers!

I have just about every suspension mod available including 18" Nitto NT05R drag radials and still can't hold traction in 1st or 2nd on concrete in this cooler air. Sure wish Mickey Thompson made an ET Street in an 18" 305 size. Those hold!

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Yah like traction. lol. I think that's where I'm going to focus my attention now. 1st and 2nd are almost useless because I can't put my foot into it without incinerating the tires! I think if you step back and look at what SVT did with these cars it's absolutely outstanding. They gave us a race car, that meets emissions.

Well said. I love mine and at the moment am making the most out of telling everyone it's stock. So when I tell them how much power it has I then say "that's out of the factory". The noise. I say "stock exhaust". Everything from grille delete to stripes to Brembo brakes, let Joe Public be shocked that this is some car as it comes.

 

However I will probably mod it at some point....

 

Regarding traction: my 2007 GT500 had a 100+rwhp kit and for traction it had: BBR LCAs with relocation brackets,Strange adjustable rear shocks, Whiteline adjustable sway bars, Toyo Proxy tyres. Dug in really well even off the line but mash the pedal and the tyres became smoke. And that's still with less power and torque than my 2013 has. What hope is there to hook these up...?

 

Malc

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Headers I have always believed in. I would, however, like to see some flow data comparing stock manifolds, shorty and long tubes on this motor. Headers on these motors seem to be in the Pain in the Ass category as far as install and day to day running - heat problems, etc... Your thoughts pls.

I have seen the stock manifolds off the 5.8. They are very restrictive. I'm going to add a set of Stainless works Headers along with O.R. H pipe ( I like the sound over the X pipe.. it has deeper tone) very soon and see if I can get the 32 H.P. I need to hit 700 RWHP with all the other mods I have already.

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I have seen the stock manifolds off the 5.8. They are very restrictive. I'm going to add a set of Stainless works Headers along with O.R. H pipe ( I like the sound over the X pipe.. it has deeper tone) very soon and see if I can get the 32 H.P. I need to hit 700 RWHP with all the other mods I have already.

700 easy with an upper pulley, intake, headers and tune. A little over 700 is real close to maxing out stock injectors and fuel pump. A boost-a-pump will take care of that assuming not too far over 700.

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I basically just used your number for that. You will, I suspect, only see that gain way up in the RPM range as that is where the headers are going to make a difference. If you watch A.M 's presentation you can see their dyno results - very impressive. So all I was trying to point out is you may not realize a huge difference. As well, will you notice another 32 hp on top of your current gains, or is it just a lot of money that could be spent somewhere else? I've studied a few dyno results from the Supersnakes, etc and the A.M. rules way above them in the torque dept. It isn't until 6000 rpm that the SS will dominate in the HP aspect, and they will never dominate in torque. Since torque is what gets you up and going and HP makes you go fast, with my setup, I rev to just over 6000 rpm and then shift; that way I drop right back into the massive torque and keep pulling. Not to make anyone upset, but, is it even worth all the money for the bigger supercharger, etc to gain more HP in the last 1000 - 1500 rpm when you have to sacrifice 100 lb ft of torque or more throughout the rpm range? It would be a great test to get both setups at the track.

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