dual exhaust for my 71 vert with stock 302

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Everwood

Well-known member
Joined
Sep 23, 2019
Messages
101
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Location
kansas
My Car
1971 mustang convertible
I am considering adding dual exhaust to my 71 convertible. She has a original 302 and original style single exhaust now.

I want to hook up to existing manifolds and use H pipe with mild flow master mufflers. 

I would appreciate any recommendations and advice. The research I've done seems pretty confusing for  exhaust systems for the 302.

Would I be better to get mufflers and have muffler shop fabricate the system or is there a good kit?

Thanks in advance

Wayne

 
You might want to consider going with headers also while your at it.  Will give you a better sound and a few extra pony's under the hood
Interesting.  is there a rule of thumb as to what a few pony's is?

Also  what does the dual exhaust over single exhaust do for performance?

 
This would depend on if there are any other mods to the engine. IE 4bbl intake and carb? Cam? Head work? Both headers and dual exhaust allow the engine to breath easier on the way out but if you did not make any modification to allow more coming in then the performance gain is less than it would be had the intake side been done as well. Mods all have to work together to get the most bang for the buck. Say you did an intake swap to a 4bbl carb and left the single exhaust and stock manifolds on, you would gain some additional power. Then decided to swap to headers and dual exhaust later on. The gain from the exhaust swap would be greater in this scenario than leaving the intake a 2bbl and swapping out the exhaust. 

 
This would depend on if there are any other mods to the engine. IE 4bbl intake and carb? Cam? Head work? Both headers and dual exhaust allow the engine to breath easier on the way out but if you did not make any modification to allow more coming in then the performance gain is less than it would be had the intake side been done as well. Mods all have to work together to get the most bang for the buck. Say you did an intake swap to a 4bbl carb and left the single exhaust and stock manifolds on, you would gain some additional power. Then decided to swap to headers and dual exhaust later on. The gain from the exhaust swap would be greater in this scenario than leaving the intake a 2bbl and swapping out the exhaust. 
For now, I am leaving the original 2bbl and all original intake. So any increase in performance would be exhaust upgrade only.

Wayne

 
Precision Exhaust is owned by Dave Eichner, who used to be one of the principles at Mustangs Unlimited. His dad Frank had a mint '73 Q-code 4 speed convertible. They are good people and will treat you right. 

 
Interesting.  is there a rule of thumb as to what a few pony's is?

Also  what does the dual exhaust over single exhaust do for performance?
On most V8's without any mods done to the engine headers will add about 20 to 30 hp.  As 73pony mentioned, a lot of factors come into play when it comes to engine mods and hp.  Adding dual exhaust with your standard manifolds will not do much more than add a few hp and a different sound.  Headers, in simple terms, allow more of the exhaust gases to fully escape the cylinders allowing for a greater amount of fresh air/fuel mixture to enter thus providing more hp and torque.

 
Is the dual exhaust system for a convertible the same as a coupe or mach body style?

Wayne

 
Is the dual exhaust system for a convertible the same as a coupe or mach body style?

Wayne
In a factory sense, yes. Ford used the same system for all body styles. 

Since a dual exhaust for a 302 is a non-factory item, then it depends on who makes it. It would be fair to assume that Precision makes their H- and mid-pipes work for convertible cars, which by default, work on all others as they don't have the underfloor reinforcements. Tail pipes and mufflers are all the same, only differentiated by turn downs or tips through the valance. 

 
Npd has h pipe, hangers, mufflers and pipes for complete system. I put one on my 73 302 mach 1 fit perfectly 

 
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