MAYHEM1

I have a 2011 5.0 and what to cut the cats out for drag stripe racing. Will the removal of them harm or mess with the back pressure?

imsonastie

you know they make mid pipes right? unbolt it for the track, then put the cats back on, but just removing the cats wont do that much, the rest of the exhaust is still restricted.

steveharris

Removing the cats will add HP, but lower torque. Kind've a 50/50 trade off. Your best bet would probably be to get a high flow cat and a tune that would utilize it. You'll gain more from an "off the shelf" tune than you would cutting the exhaust anyway.

HT

Don't cut cats...that's inhumane and cruel. They have feelings too.

But seriously, just get an O/R midpipe instead of cutting them out if you are dead set on it. Like someone else said though, most people who remove them just want a louder sound, whereas performance will probably be better with high flow cats and a tune.

JIM5.0

I like turtles!

http://www.youtube.com/watch?v=cfHnM...eature=related

MAYHEM1

Well I am going to install a new Roush cat back exhaust system next week. I was told that if I cut the cats out totally it may disrupt the back pressure needed to the motor to operate at peak performance. I've done it in the past on my 2007 4.6 GT, that is removing them and adding Flowmasters with no problems at all and with a much deeper sound which sounded great also letting a lot more unwanted air out much faster. I am a very aggressive driver and who would'nt be with this car, this being said I drive this thing on the streets like I do on the track, all out. Just dont want to do something to the car and hurt the motor while trying to gain HP.

HT

You're more likely to hurt the car driving "all out" than you are cutting the cats out. Why wouldn't you just get a new midpipe instead of cutting the cats out of the current one?

It's just not going to add enough horsepower to make a difference...especially when it reduces the torque...it's really just a sound mod. Tons of people have done it though...

Mishri

errr?? arrgghh?? wtf? I dunno where some of these people have been getting their info but it's flat out wrong.

with a cai+tune most people are seeing low 12s, some 11.9s, adding an off-road midpipe people are picking up about .2 in the 1/4.. that is a massive gain for an off-road midpipe. should be somewhere around 20whp. (id think 10-15whp is more realistic) It is a great mod to do on the 5.0 as that is the primary restriction in the exhaust, they come with factory headers so not a lot can be gained there. it's a much bigger gain than on the 4.6L 3v.

HT

I'm not talking about the strip. I'm just saying that in daily driving most people just do it for sound. Not to mention the OP doesn't sound like the sharpest tool in the shed saying he drives his car "all out" on the streets. I'm sorry, but I'd rather not have people driving like they are at a track around me. You get out all alone on a country road, you go for it, but when other people are around...that's just stupid.

Mishri

found a dynosheet:



it's a power gain throughout the entire RPM range, no loss. the header test was from JPC's 2,000 headers... i wont be getting those anytime soon, but seems to be a bigger gain than others reported.

edit: actually, its powerloss vs a catback (rarely done on these cars) up to 6300rpm, but a gain over intake+tune only. what i find very surprising is the axleback showed around a 5whp gain, didn't think you'd get any out of that (muffler only)

and teh guy said he wants to do this for drag strip racing.. so yes, he should see about a .2 gain off of throwing an off-road midpipe on there.