Remove cats or go hi-flow??

[grayman]

Have 00 GTS, considering cutting out cats and replacing with straight pipe. Any 00 GTS owners done this?

 

[JonB]

If you do NOT have a good cross section of other mods, all you will achieve is a 'ratty' sound, less side heat, check-engine open loop operation (BAD) and idle surge.....and a gawdawful STINK out the tailpipe. On an un-modded 2000+ you might even lose some torque, and pich up 2-3 HP. If you kept the OE exhaiust the TQ might be nil.

You have to ask yourself the GOAL, and is this the best way (or even any way) to achieve your goal.

At a minumum you'll needd O-2 simulators.......
For about the same cost-benefit you can add HF cats, and avoid the stink, surge, sims, rats, but get the good stuff......

 

[Qualitywires.com]

jon,

if you add on the high flow cats...will you get a louder note? I want to do the same, but I'm doing it to make my viper louder. I really don't want to contribute to the pollution more than I have to, but if I can achieve the noise level I want...this might be the way to go!

 

[Jason Heffner]

I would have to agree with John. Despite your car having a three inch cat back system, removal of the cats would only give you noise, which may be exactly what you're looking for. You would most likely see little to no gain in power with your stock headers. You should at least install a set of headers before you will start to see significant gains from removal of the cats. Remember, when you decide to go with aftermarket headers, consider where they place the oxygen sensor ****. Some headers place the sensor too far downstream for the sensor to operate properly on a 2000 car. If I were you I would consider Belangers. They can place the oxygen sensor close to the head and you will have no check engine light. Good luck.

 

[Chuck 98 RT/10]

I could not disagree more with JonB, and since Kid doesn't show up much anymore I'll make the comment about HiFlows being for the ladies.

Moving on...

Want more sound? Remove the rear muffler and gain 10hp. I can personally confirm that. ref. my 98 RT/10.

Want even more sound? Remove the cat, you'll gain 10 - 15 hp. The car will be much louder and will backfire with flames, but it sounds great! Your bumper will get discolored. I don't know what the smell is that some people complain about. ref. my 97 GTS.

Of course if you really want to spend money you're at the right place.

 

[treynor]

Ditto above. The high-flow cats WILL make your car louder, though not as loud as no cats. High-flow cats alone will pick up only a few HP & ft/lbs; combine with headers and a catback if you want substantial torque gains and modest HP gains.

If all you want is noise gain, you could go with the Snake Oyl rear muffler delete, possibly in combination with high-flow cats. That would pick up a few HP, and you'd have no risk of 'check engine' or other driveability problems.

 

[MGWLTD]

OK OK i will post this again and i hope that someone puts this in the archives!!!!!

i have owned 7 vipers and on every one of them i have played around with different combos of the exhaust from snakeoyls to striaght pipes with no cats to all sorts of combos of each. here is what i have found to be the absolute best bang for the buck...

STEP ONE- remove your side sills ans expose the cats and the big resonators just rear of the cats. have a muffler shop cut about an inch in front of the cats and about an inch behind the reosnators and remove the entire assmebly!!! not only does this decrease heat but those things weigh a ton!!!

STEP TWO- go buy some hi-flow cats but make sure you get smaller diamter ones than the stocvk. one of the main reasons the sills yellow is the cats are touching the sills in some caes.

NOW HERE IS THE MOST IMPORTANT PART.. WHEN YOU WELD IN THE CATS DO NOT PUT THEM RIGHT WHERE THE OLD ONES CAME OFF. INSTEAD PUT THEM FURTHER BACK WHERE THE SIDES BULGE OUT A BIT TO GET MORE AIR AROUND THEM!!

just have your muffler shop use good quality SS pipe and fill the gaps where you took off the resonators and connect the pieces.

STEP 3- you can either stick with this setup and leave the rear assembly alone or do one step better and cutout the factory rear muffler and weld in an h-pipe and then get borla mufflers for the rear. they look great and sound great.

STEP 4- now this step alot of you guys may not want to do but i found it really works. i take a small drill bit no bigger than 1/8 inch and drilled a mesh pattern in the black compostie material at the front of each sill right behind the front wheels. this lets air go insidfe the side sills to cool the cats and sills without letting debris and rocks get in.


trust me. this setup works and can be done total for about 400 dollars!!!! i have never had a car yellow and i can get out after a hard run and lay my hands right on the sills.

george