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Discussion Starter · #1 ·
Hello,

I have a 1968 lime-gold mustang with a 289 thats going to become my daily driveri was wondering if the tri-Y headers are worth the money, as far as performance gain? and will they fit onto a mustang with factory A/C?

Also, i am installing an Edlebrock "Air Gap" intake (twin plane i believe?) and an edlebrock 650 cfm carburetor, are these good upgrades to the factory two barrel intake? will i feel any power gains if i go with the tri-Y headers and the four barrel carb with thw "Air Gap" manifold? and how much will those upgrades affect the MPG's?

Finally, are 3.00 gears good for a daily driver, as i wont be making very many trips over 100 miles, moslty to and from school. hould i move up or down in gear ratios?

thanks for looking :wavey
 

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The power upgrades you mentioned should provide you with a little extra oomph. I'd check the air gap manifold to see if your stock hood will clear as this is a rather tall intake. The 3.00 gears should be fine as well.
 

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I am just replying to the part about the rear end ratio. Do you have to get on the highway on your way to school? If you spend a lot of time cruising over 55mph, I'd go with the 3.00. Here's the math for you.

RPM =

MPH X Trans Ratio (in high gear) X Rear End Ratio X 336

Tire Height

I am just assuming you have 27 inch tires and a final transmission ratio of 1:1.
70mph=3580 engine rpm with a 4.11 rear end
70mph=2613 engine rpm with a 3.00 rear end
 

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Idk the performer 289 is sorta a stock replacement i'd get the air gap or performer rpm regular. The air gap will most likely fit under ur hood.if not just get a smaller air cleaner. but measure first. tri-ys are good i have long tubes and they are good too just gotta make sure they will fit.
 

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I wouldn't put anything larger than a 600 cfm carb on a 289, because you don't want to lose torque. Especially for a daily driver. Torque is what you want out of a daily driver because that is what you feel on the streets. A If you are looking for some horsepower that is 250 on up, i would get some gt40 heads. I am in the process of getting some now.
 

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Discussion Starter · #7 ·
Thanks for all your respnses :bigthumbsup
i think i will leave the gear ratio alone, since i will most likely be going over 60 MPH to and from school. and, i probably wont mess with the heads since the Gt-40 heads are rather expensive for me at this moment :so.
i also found out last night that the air gap will fit under my hood if i go with a "Hi-Po" air cleaner instad of the factory blue one.

again, thanks
 
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