High flow cats

[87whtecoupe]

I have an 02 gt with longtube headers, offroad x-pipe and slp loudmouths. It sounds fantastic, but my daily is under the knife at the moment so the gt is currently my DD. It doesn't get good mpg's on the highway, it's terrible. I'm considering installing some cat converters, but will high flow cats improve fuel economy? Or should I just stick with the regular ones? Plus I may be getting old because the sound is starting to annoy me.

P.S. my everyday driver is an 88 turbo coupe, it gets 20 city/ 32 highway. It is currently in the middle of a brake conversion.
The mustang gets less than my 03 Durango, which is rated at 15 city/ 20 highway.


Thanks.

 

[trinity_gt]

Cats will not help the fuel economy of the Mustang. They will mellow out the exhaust sound though...

Check for dragging brakes, slow/lazy/contaminated O2 sensors, tire inflation etc.

 

[snowman23]

I have the MRT catted H on my 04 GT which has 2 high flow cats rather than the 4 stockers. Definite change in tone/volume of exhaust. Slight increase in throttle response. No change in fuel economy. That being said, is one of my favorite mods to date. Good luck.

 

[The Mach Life]

I had gotten mid-high 20's a few time in my 00' GT. Not kidding however when I say you have to baby it big time to get there.

Cats will only help with sound.

Do you have a CEL? What gearing? Is it warming up completely? I had to change my thermostat twice in less than 5 years time. That was worth a couple MPG every time it started sticking.