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Discussion Starter #1
hi I have a mostly stock(small dia. flowmaster catback ststem only) gt that I want to perk up a little. (I have a 84 gt for getting hard core addrenilin rushes for.) I put a lot of miles on the 95(140 a day) so economy is important but NOT imperative. I want to add 50 or so hp without killing economy.I was thinking about adding a cobra intake 70mm tb 24lbs injectors/maf gt40p heads equal length shorties x pipe and 40 series flowmasters(2 1/2 dia.) 3.55 gears/shiftkit cam choice is undecided as yet as is the ignition system. anyone ran a simular combo?what gains/economy loss could I expect? I get 24-26mpg driving nice now. it runs great and drives better(prev. owner worked the susp.w/eibach/koni and swaybars/controlarms front and rear. the engine seems weak to me(comp tests 145-150 all around) nothing is in stone as far as engine parts ar concerned just thinking out loud lol thanks
 

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I think you could go up to 3.73's without much loss in economy and I didn't see if you had a CAI or not. And why not go up to long's ?
 

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Discussion Starter #3
I feel long tubes really pay off at mid to high rpms(with the right parts) I turn 1800-2000 rpms at 65mph(speed limit w/county sheriffs hiding along the way) shorties work better in this range(more torque) as to the 3.73s I'm not sure they would hurt the economy that much compared to the increse in fun factor! I have a lincoln mkviii I went from 3.08 to 3.55 and only lost 1-2 mpg(it knocks down 28-29mpg consistantly its a great car but the dohc 4.6 is super expensive to build/overhaul i can buy a new 5.0 for what heads cost to rebuild!!!)
 

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My GT had 2.73 gears stock and swapping in 3.73s didn't change gas mileage at all. I gained 75.7rwhp/66.6rwtq and ~1mpg better gas mileage with my mods compared to bone stock.
 

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Discussion Starter #5
bullit do you have a custom tune? truthfully I expected a "hit" on economy especially with your upgrades. most of my experience is w/carbed stangs 65-68 set up for road racing(we did'nt care about economy most were around 8-10 mpg being nice never checked racing but lower) so I have a lot to learn w/injected versions.
 

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No custom tune. I still have the stock 19lb injectors but with the AFPR set at 45psi (vacuum off) and the timing set at 12*. I run 91 octane gas.
 

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Discussion Starter #7
not a lot of replys here... is anyone trying to improve both economy AND performance??? w/gas hitting 4.00 a gallon and stock 5.0's performance what it is dismal at best(the stock early 'stangs wer'nt any better... worse actually ) I was able to get 16mpg when my buddies were knocking down 10-12 and still win in the 1/4 (high 12.s mostly ) I ran a lowrise dual quad w/500 cfm afb's.I felt the better fuel distribution helped both economy and performance. the new cars excell the same way with even BETTER fuel control. anyone trying to improve both??(I'm beginning to think my best bet is a forged 7.5-1 shortblock w/vortec and moates) anyone doing this???
 
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