New Mufflers for the BDR;)

[Mark Brye]

After reading about the restrictions of many of the various cobra sidepipe systems and RedBarchetta’s Phase I sidepipe installation, I decided I wanted to do the same for my Backdraft. I think the Backdraft has a good setup and sounded great but I wanted more sound and freer flowing exhaust. I think BDR has done a good job with the stock pipes they send out as they will work perfect for the majority of the people that own them. I researched many of the different mufflers and came to the conclusion that the Stainless Specialties (SS) mufflers where the correct choice for me. My goal was to make more power and get a more aggressive sound out of the engine.
For my BDR, I ordered a 27.5 inch SS muffler with the 3 inch internal pass through/4 inch core. As it turns out, the stock BDR turnout is only 3 inch OD so I ordered a 3.5 inch turn out to later be welded to the new muffler. Another interesting note about the stock BDR set up is the collector just before the inlet of the muffler is not 3.5 inches like many other side pipes. It is actually 85mm which is about 3.35 inches. I had SS neck down the new mufflers to 3.35 on both the inlet and outlet. At 3.35 inches, the 3.5 inch turnout butts right against the outlet of the muffler and the inlet of the muffler just goes over the top of the exhaust collector. The BDR mufflers are about 6 inches longer than the comparable SPF mufflers I have seen and are different on the internals also. I believe that the SPF mufflers are a 2 inch pass through. The BDR mufflers have two tubes that pass through that are pretty small. Take a look at the pic! I am mentioning SPF mufflers in this post because those are the other stock mufflers I have seen and can relate to. I should also note here that SS told me that I should have the mufflers polished by them if I was going to get them coated. I guess that is not the case and is optional as the coaters will blast the sidepipes anyway.
After reading about mufflers for weeks on end, I came across a post in the NW Club Cobra section and found out about a couple people local to me that had added SS mufflers to their sidepipes. I contacted 1blackbb66 who had been in several of these posts and he responded, and as it turns out, he is a welder and had done several other SPF cobras in the area. I have to mention he is a hell of a nice guy also! I went to a couple cobra gatherings with him and met some nice people and also heard the SS mufflers for the first time. I sure loved the sound of Jake and Fred Hamiltons cars SPF’s with the SS mufflers. Oh my. They sound SWEET!
My mufflers showed up from SS and I took off my side pipes for 1blackbb66 to weld up. He has a jig that he made for SPF cars and modified the Jig a little to work with the BDR sidepipes. (I really have to thank him for all his help and guidance with ordering the correct mufflers). He cut the stock mufflers out, and tack welded the new ones on. He also spent some time on the SS mufflers, making them smooth where the weld joints of the internals can be seen through the casing as supplied by SS. The turn outs are set to point straight out the side and sure look a lot better than the 3 inch outlets that the stock BDR had. He then brought the sidepipes up to my place and we test fitted a couple beers and sidepipes onto the Cobra. Perfect fit! We started it up for just a little while and they are music to my ears! This is exactly how I wanted the car to sound. We only let it idle in the driveway with just a couple easy stabs of the throttle. They sound much deeper and free flowing. If you want new muffs, these are the ones for you! It gave my 392 a total Big Block Sound.
The pipes came off the car after the test fit for final welding and I hope to get them to the coaters on Monday. Then off to the dyno to see what HP/TQ improvements have been made. I am sure the car will be running lean and need to be rejetted. I have added a couple pics to my gallery if you are interested. I will try to attach them in the post but I am not so great with computers….

[Mark Brye]

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[Mark Brye]

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[pmfranke]

what do the new pipes look like inside? how much did it set you back? nice little story too.

[Mark Brye]

I do not have the internal pictures yet. But they look like the ones in this post:

Custom sidepipes - Phase I

The mufflers are about 200 a peice after shipping. The 3.5 inch turnouts are 60 a peice through Stainless Specialties. Looks like the ceramic coating is going to be 350 bucks.

[RodgerH]

Hey Mark,

I'm rapidly approaching the time to make the same decision. I'm curious, since you ceramic coated your exhaust anyway, why did you go with (much more) expensive stainless steel, vs. steel?

Rodger

[Mark Brye]

I went with stainless steel because..uummm...I guess I was not smart enough to ask Stainless Specialties if they had just a steel version of the muffler. There is no particular reason, I just asked Stainless Specialties what they had done for all the other cobra's and they told me the price.
I would surely ask them if they make them in steel if you are going to order some. From what I understand, you do not have to have them polished if you are going to have them coated. I would sugjest that you have someone grind down the casing where the SS mufflers have "seems" that show through from them welding in the internal pass through. 1blackbb66 did this on mine and they look sweet!

[Rwillia4]

This was a great information piece! I didn't know of the restriction in the pipe and I am curious what it will do for your HP/TQ. Do you have an original dyno run to compare it to?

You think yours sounds tame! It gets even more tame with FI stacks... I like you am looking for a little more sound.

[Mark Brye]

Yes, I had a perfect tune on the engine before the new pipes. So when this is all said and done, I will have the new dyno numbers to compare to the old, plus I should have the new air/fuel radio also for comparison. I will keep everyone posted.

[Dwight]

KMP

Dwight

[Rwillia4]

Mark,
Any results...even if they are not what you expected please share. I'm hope'n you have exceeded your expectations and the only reason for your long period of an updated post is your shear enjoyment of burning petrol, now that you know what you have on tap.

[Rwillia4]

BTW …I have been informed that the noise that permeates the vehicle greatly exceeds the noise present inside the vehicle during “right pedal” operations .

[Mark Brye]

RWillia4,

I am going to try to make it to the dyno next weekend. The weather is going to hold out the way it looks. Have a 100 mile trek upto the dyno so I have been waiting for the weather to shape up.
I have had the Cobra out several times now. This thing sounds so sweet. I just can't get over how much lower in frequency these new mufflers are. A buddy of mine was following me the other day and he said that when he pulled up next to me at the light, he could feel the exhaust pulses of the cobra pounding in his car. He said he thought he had a subwoofer under his seat.
I am thinking this mod should have added a fair amount of power. Good or bad, I will post the results. I know the results will be good

Mark

[lovehamr]

Mark, I know this is from an old post but I don't recall seeing any followup on the dyno. Did you ever get to dyno those puppies?

Steve

[Mark Brye]

I made two trips to the dyno which is about 100 miles away. The dyno broke down both times. I got to the end of the summer and never got the chance before parking it. Its on my list of things to do this spring. Tell you one thing, these mufflers sound sweet! Gave my car a total big block sound!
I will post the numbers when I have them.

Happy Motor'n

Mark

[lovehamr]

200 miles and it broke twice! Dang, talk about getting snake bit. Thanks for the update.

Steve

[Cashburn]

Mark,
Just wanted to add some updated information. The latest sidepipes from Backdraft (I'm guessing around car #900 or so) have one big resonator down the middle instead of the 2 little pipes you originally had.

[Jimbocobra]

Cashburn, can you post a pic? What size is it?

[Sledge]

Cashburn:

Do the newer sidepipes sound the same as the originals? I'm looking for some pipes that don't sound quite so glass-packy to put on No. 168.....

Also, are the newer pipes finished better than the ones that came with #168? They're okay but could have been much better.

Thx

[tamanaco]

anyone have other muffler options for modifying side pipes? looking for less restrictive....