View Full Version : Cat delete
gnxtc2
05-07-2008, 04:12 AM
I don't know if talk about his subject is allowed here but I'll try.
Would removing the cats help performance and leaving the stock mufflers in place? Also, would my SCT program need updating.
Billy T.
gnxtc2@aol.com
fairlane347
05-07-2008, 05:31 AM
I don't know if talk about his subject is allowed here but I'll try.
Would removing the cats help performance and leaving the stock mufflers in place? Also, would my SCT program need updating.
Billy T.
gnxtc2@aol.com
No real power gains, but if you do you need SCT update.
ctrlraven
05-07-2008, 06:15 AM
No real power gains, but if you do you need SCT update.
I don't know how power I gained but I knocked little over a tenth off my 1/4 mile and def had more pulling power during mid-high range.
I only removed my 2nd set of cats that are next to the trans, didn't touch the 1st set.
If you only remove the 2nd set you will notice a slightly louder exhaust tone and maybe a little get up and go but you don't need a tuner since the 2nd set rest behind the 2nd pair of O2 sensors.
The 1st set of cats is a whole other ballpark to deal with.
magindat
05-07-2008, 06:44 AM
Deleteing 2nd cats WILL improve flow and give a bit of low end torque. You WILL feel in the butt-o-meter.
If you already have a tune in the car, the 2nd O2's are already null in the tune. You can cut them off and leave the plugs hanging. Or you can cut behind the bungs, remove the sensors, tuck the plugs and plug the bungs. The bungs might be useful for future dyno tunes as a place to mount the wide band the dyno uses.
You WILL NOT need to get a new tune on the X-cal for such a minor mod.
ctrlraven
05-07-2008, 06:56 AM
Yeah the butt-o-meter was dead on with the speed-o-meter when racing against a crotch rocket and being able to hang with it to get a thumbs up from them. I grinned non-stop for the whole hour drive home after that lol.
oldekid
05-07-2008, 07:38 AM
Speaking of the second set of cats. I'm running with no mufflers, and on initial start up my exhaust sounds a little raspy. Once the engine warms up, that goes away.
Does anybody know if removing the rear set of cats would help that? I'm thinking maybe it's them that have to warm up, and not the engine. Anyone know?
Hopefully this is related, cause I don't mean to hijack this thread.
:beer:
ctrlraven
05-07-2008, 08:26 AM
Removing them can't hurt, give you a little more throaty sound as I noticed right away with mine.
TAKEDOWN
05-07-2008, 11:34 AM
Can you remove the second sets of cats and pass emission test, live in Chicago, which includes emission testing every so often.
ctrlraven
05-07-2008, 12:18 PM
How are they at visual inspection of under the car? Do they put your car on the treadmill or just plug into the OBD-II port, scan and take your money?
The 2nd set of cats are directly behind the 2nd set of O2 sensors so they are only reading up to that point and not after. I know of the local CAM guys removed his while still being stock and passed Maryland emissions fine. They won't throw a code if your stock or have a tune. It's a very inexpensive mod to do if you can do it yourself awesome if not just finding a shop that will can be the hard part.
TAKEDOWN
05-07-2008, 02:06 PM
ctrlraven...thanks for response and info!
ledzilla
05-07-2008, 03:00 PM
How are they at visual inspection of under the car? Do they put your car on the treadmill or just plug into the OBD-II port, scan and take your money?
Did the emission test last summer (live in Chicago burbs). All they did was plug in the cable to the OBD II port. Didn't check anything else, didn't run on the dyno. This was the Downers Grove location, btw. They didn't seem to care much about the whole thing. Just plug it in, get it out, do the next car. No money charged... They do it for free. I've been taking cars there since 1998, and that's always how it's been. Except my first car was OBD I, so they put it on the dyno.
ctrlraven
05-07-2008, 10:22 PM
Yeah if they just plug it in and send you on your way you will be fine just make sure to cut the pipe at the front part of the cat as possible because that's where the pipe is at it's straightest point of the pipe.
Measure several times, cut once lol and enjoy.
I have the 2nd set of cats removed, Flowmaster Super 40's and res-delete tips. Here are some videos
Exterior
http://youtube.com/watch?v=ngGaKzqoNZE
http://youtube.com/watch?v=qWgDVWNZjhQ
http://youtube.com/watch?v=Cj87rb4mwC4
http://youtube.com/watch?v=33lNIZe0sc4
Interior (front windows down)
http://youtube.com/watch?v=vuh4WH1jVDU
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