get gears (373's) and a h or x pipe and you'll crack into the 14's. the mufflers aren't hindering you at all at this point. they will mostly be for sound. If you want 13's get some 99 heads or a 99 motor
I still get 20-23mpg even with my mods
good luck!
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96 stang,ported 99 heads, 99 intake, 99 cams,Steeda power pullies,Kirban adj.reg.,Pro-m 87,24#inj.,70mm t/b,BBK longtube headers,Bassani x-pipe w/cats, Dynomax ultraflow catback,iat mod, home depot ram air, k@n,
373's,cobra brakes,fms spings, lakewood 90/10's and 50/50's tri-ax shifter.
best et 13.80
best mph 103.3
bfg street tires,bakersfield, ca