70 Exhaust decision. Original 2" style or N11

[Patrick H.]

Re: 70 Exhaust decision. Original 2" style or N11

The problem is that since no one sells double-walled exhaust pipes, you're not going to get the original sound from anyone's muffler no matter how it's constructed. You only have half of the equation.

[Jim T.]

Re: 70 Exhaust decision. Original 2" style or N11

With the 2 1/2 exhaust that will connect to your original exhaust manifolds I also bought from GM parts counter the piece that mounts to the transmission read mount location that fits the 2 1/2 exhaust pipes and retains them. I did mine on my 1970 a long time ago with the extra purchase bracket in front of the cross member.

[Mark E.]

Re: 70 Exhaust decision. Original 2" style or N11

With the 2 1/2 exhaust that will connect to your original exhaust manifolds I also bought from GM parts counter the piece that mounts to the transmission read mount location that fits the 2 1/2 exhaust pipes and retains them. I did mine on my 1970 a long time ago with the extra purchase bracket in front of the cross member.

Good point. This mount comes in two sizes and needs to match the pipe diameter.

[Joe L.]

Re: 70 Exhaust decision. Original 2" style or N11

The problem is that since no one sells double-walled exhaust pipes, you're not going to get the original sound from anyone's muffler no matter how it's constructed. You only have half of the equation.

Patrick------


I don't think that the pipes amount to half of the sound equation. I'd say it's more like 5% or less pipes and 95% or more mufflers. The primary purpose of the double wall pipes is durability enhancement by resistance to corrosion. A secondary benefit is less heat dispersed into the passenger compartment. There is also some noise attenuation benefit but, personally, I think it's minimal.

[Patrick H.]

Re: 70 Exhaust decision. Original 2" style or N11

Patrick------


I don't think that the pipes amount to half of the sound equation. I'd say it's more like 5% or less pipes and 95% or more mufflers. The primary purpose of the double wall pipes is durability enhancement by resistance to corrosion. A secondary benefit is less heat dispersed into the passenger compartment. There is also some noise attenuation benefit but, personally, I think it's minimal.

We were discussing it at Altoona recently, and the thought in that conversation was that the double wall did have a fair amount to do with sound. I suspect that there is a different resonance compared to the current single wall tubing, due to the weight, thickness, and isolation of the two walls. It would seem that GM spent a lot of money to specify double wall tubes when single wall would likely have gotten them through the warranty period, so there had to have been other benefits.

One of the conversants had just spent a fair amount of time talking specifics with an exhaust manufacturer, so there was some background to the conversation.