froggy47

I am thinking of having a shop make a track pipe from the stock exhaust header to the tail pipe/muffler section. Eliminate the cats and maybe replace with resonators.

1) Will I need the rear 02 "eliminators", I assume yes. How does that work, just plug them in?

2) Does the car NEED to be tuned, I'd rather not touch the tune as the pipe will be in and out several times a year, I don't want to pay to get the tune reversed & reinstalled every time. I don't care if I leave a few ponies on the table.

Will it run well without the tune option? Just cat elimination?

3) I don't want it to be much louder if any (hence the resonators). Is there a way to attenuate the sound if it turns out too loud? Some tracks ck sound now, is why.

Goal is to pick up some power without going overboard. My muffler guy can put this together for 200-300 bucks I believe.

Just post if you have some experience with this, thanks.

Supercharged111

You could have the rear O2s turned off in the tune, that's what I'd do. You'll just lose the CEL function for when the cats die in your stock pipe, but you'll probably smell that or notice the loss in power anyway. They don't affect emissions, so no concern there. I don't think the smog checkers have a way of detecting that, then you could just leave the non-functioning but still visually present rear O2s installed in the stock pipe. Shouldn't cause a retune at all (aside from the flashing to kill the rear O2s, but you want to eliminate CAGS and lower the fan temps anyway, takes 5 minutes). What kind of mufflers do you have? I really doubt you'll have sound issues with stock muffs, but possibly with aftermarket. You could just have Magnaflow glasspacks welded into the track pipe if it ends up being too loud, you muffler guy could design the track pipe with clearance for that in mind too just in case.

Snuckley

Why do al that to a stock engine ? Why do it if you don't want it loud ? Removing the hoops over the rear may need to you to drop the suspension each time- mine did.

I had a H/C LS1 with long tube headers into cats > straight pipe. Sounded great at the track. Was tough to hear a cell phone on the street depending on gear and rpm. Dyno advantage with cats and straight pipe yielded 2 hp. If you just want LOUD, just do the loudest bolt on mufflers or straight pipe. Then you don't have to drop the suspension each time....or consider those cut-outs controlled with a switch. Even though I made "no" hp with straight pipe the audio feedback on track did help keep my eyes off the tach.

Supercharged111

my guess is he doesn't want to kill cats

froggy47

I don't want loud at all, just the opposite. But I was told by more than one guy that simply eliminating stock cats was good for a good bump in hp.

Just looking for real answers. 55k on stock cats. The mufflers are stock z05 Ti which I want to keep, 1/2 the weight of most aftermarket steel muffs.

Not looking for loud or any "look" just HP and ability to easily put the original back in.

fatbillybob

I'm running stock headers and stock pipes with cat delete and standoffs on the down stream 02 and no cels. also can run stock muffler quiet or near open pipes on car now with just glasspacks. It is too loud for a streetcar but not an issue at any tracks except laguna seca. It will run fine on a stock tune but you will leave some on the table. An alternative is to just get a second ECU and have two tunes.

froggy47

Can you tell me more specifics about how the system is built. What is cat delete, what is standoff?

Do you still have an h or x connection?

fatbillybob

stock after headers. cut cat out weld in smooth pipes. H still there but x is better but IMO not worth the hassle. when you use a plug defouler bought at autoparts store under the help brand of junk you drill the center out and that screw right into the 02 sensor and stands the sensor about 1" out of the exhaust stream. This fools the system to thinking the up stream cat sees different exhaust than downstream = no lights. Our system not smart enough to want to see working DS 02 by the varying voltage. Newer cars need a sim that fluctuates or just tune out the sensor with your tune.

RapidC84B

Cat delete isn't worth much on a stockish car. There's a nice bump in volume though, but no need for extra resonators as it's not loud. Do it for weight more than anything.

froggy47

Is there a way to weld in some kind of adjuster flap (butterfly) if I needed it to lower the noise? Serious sound meter measurements where I run.

Supercharged111

I've seen just such a thing for the JDM cars, but they're aimed more at sneaking past cops and keeping your neighbors happy because when closed they are incredibly restrictive. I really think the noise won't be an issue, but you know your venues better than I.

EyeMaster

Best option, don't modify your exhaust system at all. In your case, it doesn't seem worth it and I think you're just looking for something to do.

Just removing the cats doesn't net enough HP to be worth the hassle and you create more work for yourself, are no longer "legal" (if you care), and possibly need a tune for the CEL. Noise shouldn't change too much, but it will.

Want more HP? Spend the money.

Want to go faster? Learn to drive.

waddisme

Once I get my car inspected, I switch from my Bassani to the the Borla straight pipes. I had the muffler shop splice my Bassani pipe so I can get them on and off without a lift. There is like 28lbs difference in weight. Is it louder - YES! But on the street, as long as you don't lay into it, it is not that much louder, but you can cancel out the ricer boom boxes if necessary. At the track:



When tracking season is over in December, I run the Bassani's until the next season starts.

froggy47

I "hear" ya.



Really just looking to save a few lbs and gain a few hp.

So many are saying the hp gain is minor, really? I would have guessed 5-10 hp. Anyone ever dyno with without (and not doing a tune)?

trackboss

Different car, but on my old race car (mustang american iron with about 300rwhp) I swapped straight pipes with borla xr1 mufflers on the dyno and there was only a 1hp difference. Those mufflers cut down the noise quite a bit and sounded great. The advantage of straight pipes was simply weight reduction.

moespeeds

Frog I did exactly this on my last 2 corvettes. One was a street car, the other my current track car. Just cut out the cats and weld in straight pipe, and if I were you I'd cut out the H pipe and at least open up that tiny little crossover hole to full size. On the street car the increase in noise is not bad at all. I'd try it before you jump through any hoops to make it quiter. On the track car I eliminated the mufflers and still I wouldn't call the noise bad at all.

You do not need to drop the suspension to get the hoops out, just some wiggling and they will come out, I've done it on jackstands.

I wish I had a video of the car running so you could get an idea of the noise level, but the engine is out at the moment. I'll try to dig up a youtube video of me idling and driving around the pits.

I never got any check engine lights, the car does not have to be retuned. I had the track car tuned just because I wanted some more power, but I drove the street car around with no cats and no tune for 2 years with no issues.

Don't know how much this will help, but here is what it sounds like on track. No cats, no mufflers.

froggy47

What do the cats weight vs straight pipe?

moespeeds

I can weigh them when I get a chance this weekend, but it's worth taking out. I'm gonna say in the neighborhood of 25-30 lbs. Straight pipe will be negligible, maybe 3 lbs.

froggy47

BB has some straight pipe with x for about 300 that would do it .

Local guy probably be 1/2 that but who knows how the x would come out.

No one has one of these to get rid of?

moespeeds

An X pipe is nothing to fabricate Froggy, I just got really lazy and impatient because I had to order the pre-bent sections to make it. On my street car I had a local muffler shop just make me one, they charged me like $75. My concern was where to weld it in, someone told me you can mark the pipe with a heat crayon and then see where it melts first when the car is running. If I were you I'd just get someone to measure where theirs is installed, or just put it where the current H pipe is. At the very least, cut that H pipe open and grind out the hole to full size. Mine was only like a half inch.