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There's plenty of room for the 02 sensor. Just leave as much collector as possible when you cut the old mufflers off. The collector slides inside the Slimline. Insert it just far enough to get a good weld.

Bob
Thanks!

I am going to get them ordered this weekend.
 

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I have my mufflers. It doesn't look like it will be a big deal to make some kind of a jig for the welder. Looking at my FFR ones the passenger outlet is a little crooked anyway. So I should end up with straighter pipes than what I have.

Opinions on the turnouts please. Straight out like FFR does? I like the look. Does angling them down really make any noticeable difference? How many degrees if you did?
 

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Avalanche325: I had planned to modify my sidepipes by turning the "turnout" approximately 30* down, but one of the local Cobra owners warned that doing so will result in the exhaust pulses kicking up a lot of road dust. So I decided against the turn down.
 

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Well... I'm currently OK with the FFR Noise but I'd buy a set. I wish someone would run another Sale!
Well well..... I just put mine up for sale in the classifieds. 300+shipping
 

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When I put my pipes together, set the turnouts in the same plane as the 90 degree pipes. Like the look, and makes fabbing and welding easier.
 

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I used new turnouts, has a real bend rather than being cut along the sidewall.
Total length increased by a couple of inches over stock, much lower tone, very big block sounding with my 408.


 

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Avalanche325: I had planned to modify my sidepipes by turning the "turnout" approximately 30* down, but one of the local Cobra owners warned that doing so will result in the exhaust pulses kicking up a lot of road dust. So I decided against the turn down.
Good point! I already do a pretty good job of keeping my street clean as it is.

I looked EVERYWHERE for a price better than $216.00 ea. I searched on Amazon with the part number and came up with a listing at $188. When I put it into my cart, it was $216. So, I went with Summit because I like their customer service and return policy. If someone sees something better, please post it. Summit will price match in the next 30 days.
 

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anyone use the 24"? i want to keep my Drummer Mike shields.....i know they are not needed with these but i love their look...and i think the 30s will look wrong.
 

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anyone use the 24"? i want to keep my Drummer Mike shields.....i know they are not needed with these but i love their look...and i think the 30s will look wrong.
I have Drummer Mike shields on 30" Slimlines and they look fine. I had to buy larger t-clamps.
 

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I am doing 30" as I need all of the quiet I can get with my somewhat radical cam. I have been to meetings with 30 Cobras and mine was easily the loudest. 24" would probably be fine if yours isn't that loud to start with. If I wasn't soooo loud, I would think about 24" also for the look. The other advantage of the 30" is that more of the pipe will be cooler. I think it will be one of those things that I won't notice after a week, just like the mufflers being larger diameter. I will hopefully notice that my ears don't ring even with earplugs.

If you look at pictures of originals, the FFR pipes are a little short. Most of the shots that I found, they go back to where the hip meets that body behind the door. Which for my eye, it the ideal place aesthetically. Measuring, that adds about 3 inches to the overall length. That will be easy with the 24", and not too bad with 30". There is just not a whole lot of 3 1/2" pipe at either end.

Here is my plan. Let me know if you see any issues.

Leave 1" of the straight pipe after the collector. I like the look and I can put my O2 bung in there. The turnout will be 7 3/4" long. This is just a little past where it completely straightens out. This will put the very back of the outlet right at the join line of hip and body. I am going to keep the junctions straight in both planes. I am leveled fine with the FFR pipes which are straight horizontally, so don't need to fudge any angles. I am going to keep the 90* angle for the turnouts.

How much pipe should I leave to go into the muffler? I am thinking not much at all like 1/4"?
 

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The muffler slides over the 3 1/2 inch collector, so leave it as long as possible. You can position the muffler where you want it and tack weld into place. You can also shorten the turnout some. I just finished my first real ride in my car. Drove it 100 miles. The exhaust noise didn't bother me at all. No roaring or ringing.

Bob

I am doing 30" as I need all of the quiet I can get with my somewhat radical cam. I have been to meetings with 30 Cobras and mine was easily the loudest. 24" would probably be fine if yours isn't that loud to start with. If I wasn't soooo loud, I would think about 24" also for the look. The other advantage of the 30" is that more of the pipe will be cooler. I think it will be one of those things that I won't notice after a week, just like the mufflers being larger diameter. I will hopefully notice that my ears don't ring even with earplugs.

If you look at pictures of originals, the FFR pipes are a little short. Most of the shots that I found, they go back to where the hip meets that body behind the door. Which for my eye, it the ideal place aesthetically. Measuring, that adds about 3 inches to the overall length. That will be easy with the 24", and not too bad with 30". There is just not a whole lot of 3 1/2" pipe at either end.

Here is my plan. Let me know if you see any issues.

Leave 1" of the straight pipe after the collector. I like the look and I can put my O2 bung in there. The turnout will be 7 3/4" long. This is just a little past where it completely straightens out. This will put the very back of the outlet right at the join line of hip and body. I am going to keep the junctions straight in both planes. I am leveled fine with the FFR pipes which are straight horizontally, so don't need to fudge any angles. I am going to keep the 90* angle for the turnouts.

How much pipe should I leave to go into the muffler? I am thinking not much at all like 1/4"?
 

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I finally did it! There was a LOT of polishing, caught a nasty mult-week cold, Christmas, etc. I took out all of the manufacturing marks like from the rollers, jigs, etc. Then started sanding and buffed with a kit from Cadwell that a friend loaned me hooked up to my trusty HF buffer. It did a great job. Then found a local tuner / turbo place to do the TIG welding. Including the mufflers, stress relief pads, hanger tabs, and an O2 bung, they charged me $106, for some impressive looking welds. What a deal!

I have claimed to have the loudest Cobra around. I have been in groups of 20-30 at a time, and my car was easily the loudest. I had to wear earplugs even on a ten minute drive. I was a little worried that all of the effort would not yield enough results. When I fired it up, I was shocked. No more top fuel Cobra. Now it has a deep aggressive rumble. The higher harsh biting tones are gone. My wife and I went for a 15 minute ride and we could talk. We used to have to yell at each other, most of which was "WHAT??". It will still get plenty loud at full throttle, so it's still all Cobra. I think this is going to make my car a lot more enjoyable overall.

Crazy at it is, we both touched the mufflers when we got back. We were able to put our hands on for about a second, and I'm a wimp with heat. That would have left skin on the stock mufflers and life-long scars. You won't pull over and sit on them and eat a sandwich or anything, but you will be able to get away in time if you touch them with your leg. One scar for me is enough.

I was a little baffled how you could quiet it down so much and not lose power until I cut the old mufflers out. The FFR mufflers have 2-1/2" inlet and outlet. The Flowmasters are 3-1/2".

I want to thank you guys that went before me and special thanks to bobl for the testing.
 

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I've put over 5,000 miles on mine with the 30" flowmasters last summer. 2400 miles of that driving to FFR open house for s weekend dash. Never a complaint! My partner on the drive built a set for his car after the drive!
Love that sound!
 

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Old thread, even older questions (lol)

I have the stock FFR pipes that are polished stainless steel and very purdy. They are loud, of course, but also have a sort of hammering sound (not like a baffle is rattling, just the pitch), especially on deceleration, that I'm not crazy about. I'd love to quiet them down a bit and deepen the tone. I love the look of them so I'd rather work with these if possible. The Cobra only has 1,600 miles but is 7 years old.

Did these exhausts come with fiberglass inside that maybe has settled or worn? And if I wanted to rebuild or even replace them, how does one go about "replacing" the muffler? Do you cut the welds before and after that center section, weld back in the new muffler, have it ceramic coated and then reinstall the entire thing onto the car?

I was considering the Flowmaster Slimline but they seem to be discontinued.

And what about adding those baffles that slide into the tail pipe?
 

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They were discontinued. Might give them a call and see if they can do another run. There is no fiberglass in these mufflers. Each end has a cone shape pointing inwards with lots of holes and a double skin to help keep the outer shell cooler but it does increase the overall diameter of the pipe.

The FFR pipes do have fiberglass that will eventually burn or blow out.

George
 

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I purchased a set of 24" mufflers from Classic Chambered Exhaust for my car. They have a website and are easy to deal with. They build quality products and will assist you along the way. 248-889-4364. Mike
 

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Double post...sorry
 

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I purchased a set of 24" mufflers from Classic Chambered Exhaust for my car. They have a website and are easy to deal with. They build quality products and will assist you along the way. 248-889-4364. Mike
Looks interesting! Haven't looked into the details too much, but will your heat shields fit?
 
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