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71 cougar, 466 with flattops, zero decked with d0ve-c heads, Hooker 6115 headers, all I could find to fit 71. Wieand 8012 intake 780 cfm scj oe carb. cam, undecided would like a little more of the thumper type cam sound. any help? anyone make a kit over 2 1/4" have full flow master kit know but car has manifolds.
 

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I have 3" all the way from the headers, and I think it's too large. I have heard that unless you have an engine that requires such a large pipe it becomes counterproductive. My 351w is mildly built produceing about 370 ponies. Not enough get up an go to justify the size of the got up and wents.
 

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I agree 3 inch is too big for a small ci engine though it should work good on a 466 ci engine. " Not enough get up an go to justify the size of the got up and wents." :evil:

Bill
 

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I'm sure we are talking a worked 460 block here? 2 1/2 would do... A three inch, while perhaps offering a bit more performance, will get old after a while...
 

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It depends.... I ran my car (418W) with 2.5", open, and 3". The car is overall faster with the 3" than any other combo. The 2.5" with the best mufflers I could find was killing 22HP over wide open headers (from actual dyno tests and at the track).

But now after a couple of years? The 3" is crazy loud and wears my brain out in about 15 minutes. But damn it turns heads :)
 

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2-1/2" should be plenty big for any car on the street. It is all a function of cubic inches and max rpm really...

My 393W is running through 1-3/4" 351W-swap Fox-chassis Mustang shorty headers, then a 2-1/2" Fox Mustang off-road (no catalysts) H-pipe, back to 2-1/2" DynoMax Super Turbo mufflers, then necking down to 2-1/4" tailpipes that exit at the back bumper. Back-to-back runs at the track with the headers open and through the full exhaust yielded exact same ET/MPH. I really like those DymoMax super turbo mufflers - one of the highest-flowing mufflers out there that actually quiet the car down. Then again, I'm not revving the snot out of my motor either - shifts are at 5500rpm, going through the finish at 4600 in Third - at 106mph! That is through the full dual exhaust, too!
 

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What are you doing with the car? if it is a street cat that you are driving more than racing then a 2.5 is better. If you are racing it more then a 3in would gain a few peak hp
 
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