Im new to this truck mod thing, and have a couple of questions. I have a 01 5.3L x-cab gmc with tru dual exhaust with two 3 chamber flowmasters and I am thinking of cutting off my cats for sound and performance. My questions are, will it sound good with no cats and 3 chamber flowmasters (thinking of maybe going with the 2 chamber ones). will I gain some power by cutting off the cats, and what do I do about the O2 sensors after the cats. Will I have a check engine light on with no cats? and will this do any damage with no cats? I also have a superchip programmer and coldair intake on the truck if it makes a difference.

 

First off, flowmasters suck for performance, second most people dont really notice any power gains from cutting cats (unless they are totally clogged) but it might sound a little better. Also do you have straight pipes going out the back are are they dumped @ the axle b/c if they are dumped and u cut the cats you are going to get that anoying *** drone inside the cab. If you cut the cats you could get O2 simulators or have a tuner turn off the rear O2 sensors so you dont get the SES light. Hope this helps!!

 

i got a buddy who cut his cats and actually lost power on his 5.3 tahoe

 

I had my cats off for a while with a 40 series muffler and the exhaust dumped after the axle as high up as possible and the incab noise is unbelievable. Also didn't really get any power out of it and yeah flowmaster mufflers are very great at all IMO. Magnaflow is what I am running now with cats and the truck seems to run smoother and no annoying drone in the cab.

 

I do have the staight pipes going back to the flowmasters and then turned down after that right before the axle. Where can I get the O2 simulators. I just want my truck to sound more like a race truck. The flowmasters that I have are not very loud now.

 

I picked up about a tenth in the 1/8th by cutting the cats, but it will be louder and more raspy sounding. I also lost a little bit of low end, but it makes up for it above 3k.

 

Why is everyone ******* the flowmasters? How many 10 second cars run flows? Lots

 

It's not that everyone is ******* them (I'll admit I do) but it's the fact that there are better mufflers out there for the same price or lower. Some people have proven a loss in performance with Flowmasters, in my opinion they are way overated and I wouldn't be cought running them on a scooter.

Go out and buy a Hooker Aerochamber or any other straight through design muffler, compare the flow rate between the two, and then come back here and try to praise Flowmaster. I hope I don't sound arrogrant, but I'm just stating the facts..

 

yeah and that's another thing about flowmasters, they're EVERYWHERE, i'll admit that's the only muffler i had on my vehicles at one time, but that's b/c that was what all the muffler shops were selling and praising and all that good stuff, but then i learned of all the other better mufflers out there. I dropped my flowmasters for some aerochambers and it definitely picked up some power over the flows above 3G

 

I actually picked up some SOTP feeling by cutting my cats off.... now I have no cats with a hooker aerochamber exiting in front of the rear tire and it sounds damn good!! I get alot of compliments from it, people are always asking what exhaust I have.... i