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….