Effects of Removing the Cats
4th Gear Member
Joined: Jan 2007
Posts: 1,758
From: Eureka, Ca.
RE: Effects of Removing the Cats
ORIGINAL: WhitePony02
What will be the downside of removing the cats? I heard something about it reduces low end torque because the cats create backpressure which creates the torque. But how much will really be lost? Any effect to gas mileage?
When removing the cats, what will I have to add on additionally? Will my check engine light come on?
What will be the downside of removing the cats? I heard something about it reduces low end torque because the cats create backpressure which creates the torque. But how much will really be lost? Any effect to gas mileage?
When removing the cats, what will I have to add on additionally? Will my check engine light come on?
If you remove all the cats and install dual exhaust with free flow mufflers you will lose low end tq. I removed the last 2 cats (the biggest ones) kept a single exhaust and put in a Magnaflow and I still lost s little tq down low. If you remove all the cats you will need 2 MILS for the first two 02's (closest to the engine), the second set will be fine without them.
Thread Starter
3rd Gear Member
Joined: Jan 2007
Posts: 718
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RE: Effects of Removing the Cats
I have dual exhaust already, right now I have GT takeoffs and Flow 40's. 2.25 inch tubing throughout. So I guess i'll just take the last two cats off and keep the front two on there. Does that sound pretty good? Any low drone inside the car while driving, I get one on low RPMs especially right after going into second gear.
But what would be the quickest way to swap from cats to catless and back again?
But what would be the quickest way to swap from cats to catless and back again?
4th Gear Member
Joined: Jan 2007
Posts: 1,758
From: Eureka, Ca.
RE: Effects of Removing the Cats
You could weld a flange on both ends of the pipe so they can be bolted back in if needed and do the same on the straight pipes. By keeping the front cats you won't lose as much low end tq and it will sound a lot better. I doubt you'll have any droning but if you do you can put on a couple resonator tips.
Thread Starter
3rd Gear Member
Joined: Jan 2007
Posts: 718
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RE: Effects of Removing the Cats
I was thinking something like that, and it seems like it would definitely be the quickest way. And you say I don't need mils if I only took the back two off?
Do you know where I could get some flanges?
Do you know where I could get some flanges?
Buyer Beware
Joined: Oct 2007
Posts: 3,586
RE: Effects of Removing the Cats
ORIGINAL: raz54
Man your lack of auto knowledge is scary. Yes you do need some back pressure or you will not have any low end tq. Even most race cars run a muffler of some sort and it's not just for noise, it's to get better cylinder scavenging due to "back pressure". Even in my door slammer I dropped almost 3 hundreths off my et just by adding a 2' x 2.5" straight pipe to each collector. If a totally free flowing exhaust makes the most power like you say then tell me no one runs dual 3" pipes with no cats on these cars? Because they wouldn't move under their own power is why! Next time before you open your mouth and put your foot in it AGAIN do some research and get your reply right!
ORIGINAL: Xemeth
Backpressure doesn't create torque. I have no idea why everybody thinks this. You want as little backpressure as possible for maximal power. The more backpressure, the harder the engine has to work just to push the exhaust out through the pipes. The harder the engine works doing stupid **** like that, the less power you get out of it.
Backpressure doesn't create torque. I have no idea why everybody thinks this. You want as little backpressure as possible for maximal power. The more backpressure, the harder the engine has to work just to push the exhaust out through the pipes. The harder the engine works doing stupid **** like that, the less power you get out of it.
Man your lack of auto knowledge is scary. Yes you do need some back pressure or you will not have any low end tq. Even most race cars run a muffler of some sort and it's not just for noise, it's to get better cylinder scavenging due to "back pressure". Even in my door slammer I dropped almost 3 hundreths off my et just by adding a 2' x 2.5" straight pipe to each collector. If a totally free flowing exhaust makes the most power like you say then tell me no one runs dual 3" pipes with no cats on these cars? Because they wouldn't move under their own power is why! Next time before you open your mouth and put your foot in it AGAIN do some research and get your reply right!
5th Gear Member
Joined: Aug 2007
Posts: 3,189
From:
RE: Effects of Removing the Cats
ORIGINAL: WhitePony02
I have dual exhaust already, right now I have GT takeoffs and Flow 40's. 2.25 inch tubing throughout. So I guess i'll just take the last two cats off and keep the front two on there. Does that sound pretty good? Any low drone inside the car while driving, I get one on low RPMs especially right after going into second gear.
But what would be the quickest way to swap from cats to catless and back again?
I have dual exhaust already, right now I have GT takeoffs and Flow 40's. 2.25 inch tubing throughout. So I guess i'll just take the last two cats off and keep the front two on there. Does that sound pretty good? Any low drone inside the car while driving, I get one on low RPMs especially right after going into second gear.
But what would be the quickest way to swap from cats to catless and back again?
Thread Starter
3rd Gear Member
Joined: Jan 2007
Posts: 718
From:
RE: Effects of Removing the Cats
ORIGINAL: MU71L4710N
just buy an OR midpipe. its very simple to swap them if you have access to a lift. there really is no other way, you could try welding in some sort of quick disconnect type thing to allow a solid pipe to be put in or cats but thats gonna cost some money and ingenuity and its not even worth it. u can get a used or pipe for about 100 bucks, and some random h pipe from americanmuscle for 150 shipped i think.
ORIGINAL: WhitePony02
I have dual exhaust already, right now I have GT takeoffs and Flow 40's. 2.25 inch tubing throughout. So I guess i'll just take the last two cats off and keep the front two on there. Does that sound pretty good? Any low drone inside the car while driving, I get one on low RPMs especially right after going into second gear.
But what would be the quickest way to swap from cats to catless and back again?
I have dual exhaust already, right now I have GT takeoffs and Flow 40's. 2.25 inch tubing throughout. So I guess i'll just take the last two cats off and keep the front two on there. Does that sound pretty good? Any low drone inside the car while driving, I get one on low RPMs especially right after going into second gear.
But what would be the quickest way to swap from cats to catless and back again?
4th Gear Member
Joined: Jan 2007
Posts: 1,758
From: Eureka, Ca.
RE: Effects of Removing the Cats
ORIGINAL: WhitePony02
I was thinking something like that, and it seems like it would definitely be the quickest way. And you say I don't need mils if I only took the back two off?
Do you know where I could get some flanges?
I was thinking something like that, and it seems like it would definitely be the quickest way. And you say I don't need mils if I only took the back two off?
Do you know where I could get some flanges?
That's right, you won't need any MILs if you only remove the last two cats. You will need a couple bungs to weld into the new straight pipes but you can get them at any muffler shop. Just weld them in and reinstall the 02's. Make sure you do NOT touch the part of the 02's that go into the pipe with your fingers. That little bit of oil is enough some times to set off the CEL.
VCS_SSSTANG. That may be so but they still have 'some' back pressure and you are proving my point. Those motors have very little low end tq, they make their power high in the rpm range where we need it lower so we need more back pressure but even they have some back pressure.
Buyer Beware
Joined: Oct 2007
Posts: 3,586
RE: Effects of Removing the Cats
ORIGINAL: raz54
That's right, you won't need any MILs if you only remove the last two cats. You will need a couple bungs to weld into the new straight pipes but you can get them at any muffler shop. Just weld them in and reinstall the 02's. Make sure you do NOT touch the part of the 02's that go into the pipe with your fingers. That little bit of oil is enough some times to set off the CEL.
VCS_SSSTANG. That may be so but they still have 'some' back pressure and you are proving my point. Those motors have very little low end tq, they make their power high in the rpm range where we need it lower so we need more back pressure but even they have some back pressure.
ORIGINAL: WhitePony02
I was thinking something like that, and it seems like it would definitely be the quickest way. And you say I don't need mils if I only took the back two off?
Do you know where I could get some flanges?
I was thinking something like that, and it seems like it would definitely be the quickest way. And you say I don't need mils if I only took the back two off?
Do you know where I could get some flanges?
That's right, you won't need any MILs if you only remove the last two cats. You will need a couple bungs to weld into the new straight pipes but you can get them at any muffler shop. Just weld them in and reinstall the 02's. Make sure you do NOT touch the part of the 02's that go into the pipe with your fingers. That little bit of oil is enough some times to set off the CEL.
VCS_SSSTANG. That may be so but they still have 'some' back pressure and you are proving my point. Those motors have very little low end tq, they make their power high in the rpm range where we need it lower so we need more back pressure but even they have some back pressure.
4th Gear Member
Joined: Jan 2007
Posts: 1,758
From: Eureka, Ca.
RE: Effects of Removing the Cats
I said we lose "low end" tq. That means we no longer have good power down low where we spend most of the time driving. Moving it up is a good thing if you are only racing but it's not good in a daily driver.