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Discussion Starter #1
Hey all,

Looking to get a set of headers for my 351w in a 65 mustang. Theres a set of swap mid length headers out there by Hedman that I want. I have read that long tube headers give better mid to high rpm performance and the mid lengths give better low end to mid range power (I spend more time in the low to mid range). Can anyone speak to the performance increase going from manifolds to the mid length headers (I know it will increase but can anyone say roughly by how much)? Also, I am soon going to move up to E Street heads from Edelbrock and wanted to know if anyone knew if they were compatible?

351W- Stock except for Performer intake and 4 barrel carb swap. C4 trans. 3.80 gears. Dual exhaust.

Planned - Comp Cam XE262h + valve train, Edelbrock E Street heads.
 

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Unfortunately, you do not have your engine mods done, so the increase in hp for your headers will be small, probably like 10-15hp at the most at this time, once the others mods are done, it will probably be more, most headers only give about 15-25hp increase on average. The 4b carb and intake and camshaft change are the 2 biggest changes for these engines, the free flowing dual exhaust with headers and head complement the intake and camshaft. Your camshaft selection looks pretty good for a mostly street car. Good Luck.
 

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The rule in the old hotrodding horsepower building books is called the rule of 8's. You gain approx 8 hp going from stock manifold to shorty and another 8 going from shorty to long tube.


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Discussion Starter #4
I see, this is what I kind of figured. Ok, lets say I do the heads and cam and then put the manifolds on and then switch to headers, what would my gain going from manifolds to headers be then? (I dont plan on having manifolds with the heads and cam for long anyway). Thanks
 

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I see, this is what I kind of figured. Ok, lets say I do the heads and cam and then put the manifolds on and then switch to headers, what would my gain going from manifolds to headers be then? (I dont plan on having manifolds with the heads and cam for long anyway). Thanks

That's what I just told you


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