cats

**Mitternacht** · 12-04-2007, 09:33 PM

I got longtube headers, an x pipe w/ cats and flowmasters as my exhaust setup. I wasn't happy with the sound of tyhe flowmasters and was thinking of switching to dynomaxes, but someone told me that removing my cats would help greatly with the sound.

So, do cats really affect sound that much? If so, anyone got an offroad x-pipe?

**wick** · 12-04-2007, 09:40 PM

Cats quiet it way down.

**White5.0** · 12-04-2007, 09:50 PM

Yes it defiantly affects the sound. if you want it louder, go with an offroad X or H

**INSANELY CRAZY** · 12-04-2007, 10:53 PM

oh yea... take 'em off, you'll be happy you did..

**Rowleyxlt619** · 12-04-2007, 11:03 PM

yeah the cats will improve the performance as well as the sound of the car... i removed my cats on my gt and picked up 5 tenths on the quarter mile... and that was just with shorty headers the mac cat back and a cold air intake with 3.73 gears... now i have long tubes wit an o/r x and mac mufflers... as for emissions the car will pass with out the cats if you have all obd II junk turned off... i have the diablo sport tuner for my gt and turned everything off and ran it through the emissions machine and it past as if it had the cats unless if you live in a county where you dont need the emissions sticker...

**92306gt** · 12-04-2007, 11:05 PM

no cats = more power,better sound

**u1arunit** · 12-04-2007, 11:08 PM

What don't you like about the sound? Volume or tone?

Flows should sound mean depending on which series you get.

I have Super 40 series 2 chambers and a Mac Pro Chamber and the volume is on par with a car that has a hi flow catted x pipe. I know this because I used to have one. It's a *little* louder but not *that* much with the cat-less Pro Chamber.

**scott5** · 12-04-2007, 11:20 PM

get those things off there

**Mitternacht** · 12-04-2007, 11:33 PM

I'm kinda worried though, when I take them off if it'll screw with the engine tune.

**White5.0** · 12-04-2007, 11:42 PM

Originally Posted by Mitternacht

I'm kinda worried though, when I take them off if it'll screw with the engine tune.

highly doubt it will mess with the tune, its not a major change or anything. although it may run a bit leaner but nothing too serious. all the cats do is reduce emissions. by taking them off you will increase exhaust flow and pick up a couple HP, nothing major.

**u1arunit** · 12-04-2007, 11:45 PM

Originally Posted by Mitternacht

I'm kinda worried though, when I take them off if it'll screw with the engine tune.

Ask Burntire about what happens to the tune when you remove cats.

He needed to make changes to his tune to keep from going leaner.

As I preach ALL THE TIME, get a good wideband O2, install, learn, and use it.

**SonofaBish** · 12-05-2007, 07:53 AM

I agree with Mark ^... FI is way too fragile to do something like that and not mess with the tune... N/A you could get away with it and the car would till run fine, but I'd imagine it will run lean ....

Do everything you wanna do over the winter, and come spring have it retuned!

**White5.0** · 12-05-2007, 11:13 AM

o well let me take back my last post then....i did not know that you were running a supercharger....in that case i would worry about the tune...i thought you were N/A

**Mitternacht** · 12-05-2007, 11:36 AM

Ok, thanks for the help guys. I appreciate it!

**2001GTTT** · 12-05-2007, 03:35 PM

i have a mac offroad h-pipe for sale...if your interested, and on my car it definitely made a huge difference in sound, not to mention picking up a few ponies

**Viper_ed** · 12-05-2007, 03:52 PM

Originally Posted by 2001GTTT

i have a mac offroad h-pipe for sale...if your interested, and on my car it definitely made a huge difference in sound, not to mention picking up a few ponies

He has longtube headers

**2001GTTT** · 12-05-2007, 04:07 PM

yea mustve missed that one the first time around....THANKS ED!

**wick** · 12-06-2007, 07:07 AM

Originally Posted by u1arunit

get a good wideband O2, install, learn, and use it.

YES YES YES!!!!! I think that was brought up in last weeks discussion.

**mineralrob** · 12-06-2007, 07:35 AM

Thats strange though even though you had a catted x with the flows the sound should've been decent. When i had just weld in super 40's alot of people thought i had an offroad pipe and it was def loud. It seems though when u add the offroad x/h it kinda amplifies the sound or adds a certain touch to it. From my personal experience the offroad(or catless)made it much louder though overall,on the lowend and up top.

**65 Fastback** · 12-06-2007, 11:03 AM

Unless you have Classic plates or use your car less than a couple of hundred miles a year I would think twice. Our State Inpection/Emissions tests are tough. I did this on my '87 which has Classic plates, and got flak from various mechanics. The sound was a little too rough for my tastes witout the cats so I put on 2 high flow BBK cats which still make a nice sound with my Edelbrock mufflers.