Opinions about hollowing out cats and what mods won't hurt mileage greatly?
Hey guys, just thinking of a few things. What do you think about hollowing out my cats and whatever those other two things are on the h pipe, if this is a decent idea how do I do it? Next, what mods help or just don't hurt gas mileage. Finally how do gears affect mileage, i've heard people say they'll have better mileage after gears but i didn't think it worked like that.
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1995 GT 5.0
CAI, American Thunder Cat-back, Mac O/R H-pipe, 180* thermostat, Steeda Tri-Ax shifter, Steeda rear swaybar, Urethane bushings, MSD coil, King Cobra clutch & flywheel, GT40 Intake Manifold, ~1800 watt sound system
In strictly city driving, a numericly higher gear might increase mileage. Say
going from a 2.73 to no more than a 3.55 . If you do gut those cats,
DON'T touch or breath any of the dust. Wear gloves and use some sort of
breathing protection - I've heard that that stuff is way poisonous.
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1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads!
My advice, don't hollow out the cats. They act as resonating chambers when they're hollow, and it's really annoying. Just buy an off road H or X pipe. You can get em brand new for $140 or used for $75ish.
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"If a man hasn't found something worth dying for, he isn't fit to live." - Martin Luther King Jr.
Im pretty sure you can get away with doing all exhaust mods (X pipe, high flow mufflers, and your choice of headers)without suffering mileage loss if you maintain the same driving style.
A CAI intake help mileage some but the main thing is the factory paper filter allows airflow similiar to a substance called crap. K&n has always been recognized as the best and is reuseable.
What kind of mileage are you getting now and what is still acceptable?
Well, right now I think I get about 17-18 mpg. That's an average of city and highway, but I do alot of highway driving because my girlfriend lives forty minutes away. As far as what is acceptable, pretty much anything not worse than what I have right now. I want to start modding my car and I already have a CAI, but I just don't want to lose mileage because I drive it way too much for the trade off to be worth it.
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1995 GT 5.0
CAI, American Thunder Cat-back, Mac O/R H-pipe, 180* thermostat, Steeda Tri-Ax shifter, Steeda rear swaybar, Urethane bushings, MSD coil, King Cobra clutch & flywheel, GT40 Intake Manifold, ~1800 watt sound system
Youve got something not quite right, because that 5.0, even with the extra 300 lbs. considering its an SN95, you should be getting at least 19. In my 88 I get 20 with mainly city driving, and every injector i have leaks. You may need a tune up or something, it could a lot of things. From what Ive heard as long as you keep your 19# injectors and, excluding gears, and bigger tires, you should get better gas mileage with most any mod. Even things like superchargers will increase your mileage, as long as youre not driving with the pedal to the floor the whole time...
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Cardinal Red '88 GT 5 speed, Cobra Upper/Lower, Dynomax complete Super-Turbo cat-back system, Turbo Coupe Rear 10" discs, 3:73 gears, SN95 Master Cylinder, Summit Racing adjustable proportioning valve, Spec Stage II kevlar clutch, steeda adjustable cable/quadrant, 73mm front calipers, P.A. Performance 130 amp alternator, 99 Contour Electric Dual Fans, Battery relocated, rebuilt 91 T-5, Mass Air conversion
Cats only consume 1-2% of your power, but they eliminate the majority of emissions. Do us all a favor and leave them on. Make your five horsepower somewhere else. CAI is a joke unless you have a modded motor and really need it. bbk and mac systems are ok for small modded motors, say up to 300 horse. After that they become a restriction and you need something like an anderson power pipe.
The reason for gutting the cats was to be able to ditch smog pump because I heard disconnecting the pump with the cats causes problems. Anyone know anything about this? Oh, and yeah stangboy unfortunately that is what I'm getting, and I am gonna give it a tune up.
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1995 GT 5.0
CAI, American Thunder Cat-back, Mac O/R H-pipe, 180* thermostat, Steeda Tri-Ax shifter, Steeda rear swaybar, Urethane bushings, MSD coil, King Cobra clutch & flywheel, GT40 Intake Manifold, ~1800 watt sound system
Opinions about hollowing out cats and what mods won't hurt mileage greatly? 
