Deleting rear cats

[Marylandrauder]

I found someone to delete my rear cats, my question is this ok on a stock car with no tune, will this cause driveability problems, do the front and rear cats correspond with each other on a stock car, I also plan on doing resonator delete tips, I was thinking of replacing the mufflers but wondered if it would be to loud, I noticed that the o2 sensors are in front of the first set of cats but behind the second set of cats, should i get the cats gutted out or put in a straight piece of pipe, when i was at safford on june 16th for the show one guy had his rear converters removed but i think he had a tune, i go for emissions testing in august but i heard all they do is plug into your computer to see if there are any codes, again i dont plan on doing a tune that is why i am wondering if deleting the rear cats is ok or am i going to have driveability problems, any advice would be gratly appreciated.

[ctrlraven]

That would be me. Didn't have any problems with it at all. Did notice a slight mpg increase, exhaust tone was a little louder and felt a little more power.

I do have a Xcal2 tune, flowmaster 40 series mufflers and res-delete tips extended out 1.5" past the bumper to help cut down on the interior drone noise.

Just do one thing at a time, take the rear cats off and see how it sounds to you. If it's just right then leave the rest of the exhaust alone, if you still want some more rumble then get some res-delete tips and if that still doesn't do it for you aftermarket mufflers. You have a wide range of mufflers to go with so that will just be personal preference on what you will like.

[kartherma]

I also have the rear cat delete. I went with a simple chop'em out and put in a straight pipe. For me, that is ok because there is no emissions inspection. If there were...I surely would not chop them out. Even if your emissions test is only a code check and not an actual exhaust gas sampling they may still do a visual inspection.

I have the flowmaster 40's with the rear cat delete, normal megs tips...it is about twice as loud as the other marauder I own that has only the 40's. It is an aggressive sound that can at times be annoying...like when you had that third beer and want to get home quietly.

as far as the tuning part, i think that you can get along just fine with the stock tune. the 02 sensors are located after the first set (closest to the engine).

My exhaust shop guy was all for this mod when i went in for the stock muffler to flowmaster 40 change out. when he got under the car and saw the four cats, he jumped all over it and offered to do it for 10 bucks a side (added 20 bucks to the job...not bad). His standpoint was that it is (according to him) legal in arizona and it would add sound and release some of the back pressure on the engine.

be good!
Curt

[supa_carrot]

I too am considering deleting my second set of cats, the only thing that I wonder about, is how much louder will it make my exhaust? I currently have the Flowmaster Super 40's, and they made the car quite louder than stock, so how much louder should I expect the car to be if I deleted the cats? I do suppose though if it I did it, and it wasn't loud enough, I could try to get some non-res tips.

P.S. There are no emissions testing here in Kentucky, so I don't have that to worry about.

[ctrlraven]

Here is exactly what it will sound like with rear cats delete, flowmaster 40's and res-delete tips. Yes it will make your car louder, the exhaust will be more free flowing and you will feel a little bit of increase in power in the mid-rpm range.
ngGaKzqoNZEqWgDVWNZjhQCj87rb4m wC433lNIZe0sc4

[Marylandrauder]

They dont do a visual inspection in my state, it sounds like it will be okay to do, I will probably do the rear cats first and see how it sounds, if it is not loud enough then maybe the resonator delete tips, as i said before they just plug into the computer to see if there are codes, I know on the reinhart exhaust with the cobra manifolds they have 2 converters, wondering if i should wait until after emissions, are the rear cats more restrictive than the front ones, at safford on the 16th of june one guy stated he can go 50 miles more on a tank of gas, if anyone else has deleted the rear cats and gone through emissions, please chime in.

[ctrlraven]

If you have them removed, just make sure the piece of pipe is put on good and their are no leaks. You will be fine. The front and rear cats are the same exact units, the only reason why their is a 2nd set is to help catch and clean whatever the 1st set misses.

[Marylandrauder]

Have not heard anyone say that I will be throwing codes, I am going to make the appointment tomorrow, I hope to see you guys in Hagerstown, MD. in early August.

[ctrlraven]

You won't throw any codes, sorry for not saying exactly that. I had included that when I said "Didn't have any problems at all".

The rear cats sit behind the rear O2 sensor anyways.

You can always just go get your vehicle emissions done early and then go to get the rear cats removed. That way the emissions are done and out of the way for 2 years.

[Marylandrauder]

Thanks for the reply, I am having it done on friday the guy is charging me $150.00 , i am sure i could find it cheaper but he is close by and has done work on my cars before, i talked to a buddy of mine at chevrolet and he said the same thing that as long as the o2 sensors are in front of the rear converters i will be fine, you have to let me know if you are going to be in Hagerstown the first week in August, otherwise we should meet because I would like to see your car, I dont think Gaithersburg is that far from Jessup, hope you dont live next to the jail in Jessup if it is still there.

[fastblackmerc]

Deleting the rear cats is fine, you won't throw any codes and you'll have less back pressure. You can delete the rear O2 sensors also, although you may need a tune to make sure they aren't read by the OBDII. Whay not go all the way and get some hi-flow cats to replace the remaing 2 stock cats? I'd go with Magnaflows for the mufflers.

[Raudermaster]

I'd give you a video clip of mine, but I have full exhaust, ctrlraven's is the best you'll hear close to stock since he has only muffler's and rear cat's gone. Sounds good too!

[Marylandrauder]

I thought there were only 2 o2 sensors, when I got underneath the car I saw 2 sensors after the first set of cats, I dont think there are any sensors after the second set of cats, I will check tonite, I am going for my test in august, they just plug into the spot underneath my dash to see if there any codes, I have to wait till then because i missed my last date, they are supposed to mail me something soon, whats the point of deleting the two rear sensors, where are they, if they are behind the first set of cats I should be fine, I have listened to cars with the magnaflows, a little to loud for me, cats first, maybe resonator delete tips if I want more sound then maybe mufflers.

[ctrlraven]

I'd give you a video clip of mine, but I have full exhaust, ctrlraven's is the best you'll hear close to stock since he has only muffler's and rear cat's gone. Sounds good too!

Thanks, yeah hopefully I can get some long tubes before MVV.

Marylandmarauder, just an fyi. If you go rear cats delete, flowmaster 40 series and res delete tips this is what the inside will sound like, Drone FTL :alone:

http://youtube.com/watch?v=vuh4WH1jVDU
vuh4WH1jVDU

[ctrlraven]

I thought there were only 2 o2 sensors, when I got underneath the car I saw 2 sensors after the first set of cats, I dont think there are any sensors after the second set of cats, I will check tonite, I am going for my test in august, they just plug into the spot underneath my dash to see if there any codes, I have to wait till then because i missed my last date, they are supposed to mail me something soon, whats the point of deleting the two rear sensors, where are they, if they are behind the first set of cats I should be fine, I have listened to cars with the magnaflows, a little to loud for me, cats first, maybe resonator delete tips if I want more sound then maybe mufflers.

Their is a set of O2 sensors in the first pair of cats, then the second set is what you saw which is in between the 1st and 2nd cat.

[Local Boy]

That's some GOOD video's...Thanks for the motivation...ALOHA

[Marylandrauder]

Hey guys, I emailed dennis reinhart, he said it would throw a code, he said his tune can delete the rear sensors, can I just do the part on the tune that deletes the rear cats, can the x-cal2 be used to just delete the rear sensors or do I have to have a special tune.

[ctrlraven]

I don't know why it would throw a code when the 2nd O2 sensor is in front of the rear cats. Even without a tune I went radical and deleted the whole rear exhaust and went side pipes right off the H-pipe without a tune, didn't have any problems.

You should really get a Xcal2 tune anyways, it really brings the car to life and makes it that much more fun to drive. Reinhart's tune does turn off the rear O2 sensors, I went through emissions with the tune and sensors turned off without any problems.

[Marylandrauder]

So you are saying you went through emissions on a stock tune with no rear converters and passed, meaning you did not produce any codes, if that is the case then I will reschedule getting my rear converters off, do you think $150.00 labor is too much to get the cats off, how has the x-cal2 changed the way the car runs, if you drive normal does it change your gas mileage.