James Cole

In Sound, performance and MPG. I have not decided to remove them yet, I am just looking for input, and please stay on thesubject.

Thanks in advance.

mustangman2424

I assume the sound will be much louder, MPG may go up a little. I also think that it's illegal in all the states to remove the cats, could be wrong though.

justiniida

you correct, its illegal in most states

mac10chap

Ford put extrememly high flow cats on the 05+ Mustangs so there really is no performance gain from removing the cats. Mustangman is correct, it is illegal so you will have to find someone willing to slap an inspection sticker on your car for $50 or so; thats what i had to do. as far as sound is concerned, i am sure it would be a bit louder but probably not much. the only reason i decided to eliminate the cats was b/c i saved a few hundred dollars by going with the O/R H pipe vs. the Catted Pipe.

RUFDRAFT

Are you a teacher?

Lees07GT

The biggestresult of removing the cats is that you will greatly increase the amount of pollution your vehicle emits. Do us all a favor and leave the cats in place.

Stang Skeleton

Removing the cats will make your car significantly louder (good loud), as well as gain you 3-8rwhp when tuned,depending on your exhaust set up (headers, x, etc) If you do decide to take off your cats, try and get it tuned so your O2's and Air Fuels are precise.

davesiar

Sorry to get off the topic, but where did you find those FR500's at MAC10CHAP? Do you have any other pics of your car with those wheels. Your car looks awesome!!

Menace

I disagree and so do many others. Removing of the cats dropped my 1/4 time by .02. That's a pretty good gain for $180. Anyway, the reason I went back to my cats is because I don't like the way the car sounds without cats. Removing the cats also amplifies your exhaust by like 10. I had the O/R H-pipe and SLP Loudmouths, then had resonators installed to try and fix the uneven sounds of the exhaust. Finally the fix was putting the cats back on. Now I plan on redoing my entire exhaust with a Dynatech LT Setup with High flow cats, running into 40 series flowmasters.

2oo5stang

The SLP is makiing it too loud. U will get a more louder, aggressive, muscle car sound. but Ford did do something right with the stock mid pipe,it flows alot better. You'll gain some HP but not alot like previous mustangs. It's illegal in all states, but some check for it and some don't. I know in SC, TN, and FL they have no checks so people have offroad X/H pipes all the time.