[beartracks]

I'm considering the Flowmaster muffler but don't want to get too loud. Previous post left me confused on how much sound increase I could get. Anyone running them? Especially don't want to get any cab resonance.

Bear Tracks

[SportsPix]

Originally Posted by beartracks

I'm considering the Flowmaster muffler but don't want to get too loud. Previous post left me confused on how much sound increase I could get. Anyone running them? Especially don't want to get any cab resonance.

Bear Tracks

Bear,

If you don't want to get loud and don't want resonance inside don't change your mufflers! The stock '05 GT mufflers are very good flowing and you will gain minimal if any power from adding them even if you have added g the best headers, X-pipe and race cats. I've already done the whole shebang and the one thing I went back on was the mufflers because of noise even though the JBA mufflers I installed are some of the quietest of the aftermarket mufflers.

Most of the aftermarket axle-backs are "straight through" designs that have a perforated tube from the inlet to the outlet with packing material wraped around the tube filling the muffler body. These all start out good and loud and get even louder as the packing blows out. The chambered designs like the JBA and Flowmaster work to make the car quieter in a different way and do not rely on packing in the muffler body so they do not get louder as they age. Even so the chambered designs just like the perforated tube mufflers will have a resonace point and this will change depending on your headers, X or H pipe and cats flow and resonance frequencies.

Every part of the exhaust system influences the sound and resonace frequency of the system so when you change one part what you might have thought was acceptable noise before the change may be altered with the addition of a new exhaust component. In my case I started with stock exhaust and planed to have JBA install their JBA shorty headers and a Magnaflow Tru-X Pipe with high flow OBDII cats. But JBA wouldn't install the Magnaflow Tru-X Pipe and they cut me a really good deal on their rear mufflers so I bought them. Now this souned really good and was not too loud and had minmal resonaces and the car was snappy and I was happy! But I knew that there was more power to be had from the Magnaflow Tru-X Pipe and high flow cats so I bought and installed the Tru-X Pipe. Now that woke up the car along with the whole neighborhood. But with the improved flow and the X-pipe design the resonant frequency changed and it was now very strongly heard from 2,000-3,000 RPM in and out of the car when cold. As it warms up it goes away and then sounds great but it takes a few minutes to go away. The car is also now LOUD all the time so I pulled the JBA mufflers off and installed the stock Ford pieces and the car is again prety quiet at normal speeds around town but clearly has that special "something under the hood" sound of the headers and X-pipe comming through when ever I get one it. This new sound is the best of both worlds really and there is no noticable loss in power and it seems to have helped the midrange torque curve but I won't know this until I get it back to the dyno to see if there is any change and if so which direction it went.

In closing, BE CAREFULL if you don't want to add unwanted resonaces and noise to your daily driver! Headers and a catted X-pipe with stock mufflers is probably the best solution for best overall performance with minimal noise addition. If you must change the exhaust be sure you hear the whole system as it will be when completed, not just the rear mufflers if you want to add headers or change the mid-pipes and/or cats.

HTH

[RTH Jimmy]

I had the American Thunder Flows but went back to stock. The droan was too much for me. It was a very low, deep toned frequency that went directly to my brain . This was in the 2000 RPM range especially when it was in top gear and the throttle was being pushed slightly. I also have an Automatic.

Just so you know, I am 30 years old and have had many loud cars but this one for some reason did a number on me.

[franksgt]

If you don,t want any resonance at all and a nice sounding muffler try out CORSA mufflers there a little high priced but ther great. You can hear a sound clip at www.corsaperf.com

[SportsPix]

Originally Posted by franksgt

If you don,t want any resonance at all and a nice sounding muffler try out CORSA mufflers there a little high priced but ther great. You can hear a sound clip at www.corsaperf.com

Bear,

I've heard the Corsa axle backs on a C5 Corvette (the guy lives down the street from me so I hear it every day), and an '05 GT, they are both pretty loud and get VERY loud when you are on the throttle hard at any kind of mid to high RPM. The Corsa's muff design is an atypical straight through design with a twist. Instead of relying on the friction of the expanding gases through SS packing ala Steeda, Magnaflow, Bassani et al., Corsa uses friction much as a chambered muff design does but tunes the resonant frequency(ies), to a higer value trying to avoid the dreaded drone typical of conventional chambered muffs at part throttle and low RPM. The Corsas are a small-medium volume can design, very nice cans though very expensive. They also make the same charateristic "whaaa" sound a lot of high performance european 6's make granted the "whaaa" is an octave lower but the charateristic sound is surprisingly similar in person and there is a lot less V8 "body" comming through. Internet audio clips are NOT a good indication of what ANY of these muffs sound like.

Corsa also makes some pretty high power claims for the '05 GT that are VERY hard to believe seeing that most independant chassis dyno tests and Fords own internal enginering tests has shown that Stock Ford muffs are good for 425 crank HP. As I said, I switched back to the stock For muffs and there was no detectable loss on top (time to dist. or MPH), and there may even have been an improvement in the midrange RPM. I have not dyno'd this combo yet so I don't know for sure but it feels like the stockers are as good as Ford says they are.

IMO you should save your money and buy a good CAI (Steeda, C&L, K&N), and ECU programer (Predator or SCT X2 once they fix the software). The truth is that axle back exhaust mods have the lowest HP to dollar ratio of any engine mod out there and spending more for an axle back just makes this ratio worse.

HTH

[tfaucett]

I put the flowmasters on last week and I am very pleased with the sound. It is not that much louder than stock. I am 34 years old and have had other mustangs with the off road h pipe and felt they were too loud. Other than the flowmasters my exhaust is stock. I dont feel any power difference. However as a point to be considered: If you are doing your own install I would consider the Corsa, Magnaflow, or Steeda mufflers because their design allowns for much better hanger access. It took me about two hours with the flowmaster to get them perfectly exiting the vehicle. The left rear bottem bolt is a pain! Hope this helps.

[nbk13nw]

Originally Posted by tfaucett

I put the flowmasters on last week and I am very pleased with the sound. It is not that much louder than stock. I am 34 years old and have had other mustangs with the off road h pipe and felt they were too loud. Other than the flowmasters my exhaust is stock. I dont feel any power difference. However as a point to be considered: If you are doing your own install I would consider the Corsa, Magnaflow, or Steeda mufflers because their design allowns for much better hanger access. It took me about two hours with the flowmaster to get them perfectly exiting the vehicle. The left rear bottem bolt is a pain! Hope this helps.

Several thousand miles on my American Thunders and I absolutely love the sound. Mine is a daily driver of about 35 miles each way to work. Some drone at around 1500 but not bad at all. I agree that the install of the upper hanger near the tips are really tight and took some contorsions to get at, but otherwise, about an hour job and they look and sound great!

[beartracks]

Thanks for the feed back. I'm not considering any other exhaust mods. In fact I am seriously considering waiting till the three year warranty expires and then putting on a driven supercharger along with intake mods and flash.
Sort of wake up the old girl to celibrate paying it off. I don't expect any HP gains from the FlowMasters.

[crdshrp]

I am considering bassani X pipe with magnaflow magnapacks.