true dual exhaust anyone?

**whitcomb** · 04-13-2008

has anyone yet put true dual exhaust on a l67 setup, im goin to on my gtp just wondering if im the first? ill be doin 2 1/4 or 2 1/2 depending on how much room there is....i really think it will help with the sound of my cam. give it a lumpier sound..

**SyntheticShield** · 04-13-2008

You know, I have given some thought to that before. My thinking was that if everyone uses a 3" exhaust, then why not run two 1.5" or 1.75" pipes? The only two problem areas I see would be making the bends and clearance at the firewall and then the bend around the gas tank.

You'd have an issue with the catalytic converter if you are running one in that the PCM is not set up for two of them. The only solution I would see to the first O2 sensor and the catalytic converter would be to come into one pipe, put an O2 sensor there, then a single large catalytic converter, then the second O2 behind that and split out the pipes again.

Even if you use no cat, you still would have to join front and rear manifolds somewhere to accommodate the first O2 sensor.

**whitcomb** · 04-13-2008

hmm yea im an idiot i didnt think much of the o2's , i have pacesetter headers and i was just gonna start where the front and rear meet at the y , so it setup perfect for runnin the duals i just didnt think bout the o2's , i should be ok though , im runnin a simulater for the rear o2 and the front o2 in the rear header only runs off the back bank anyways so i should be fine ?no?

**SyntheticShield** · 04-13-2008

I would caution against that. You need to take your O2 readings from the front and rear banks. The OEM set up has the O2 at the Y where they two banks join together.

**Sabrewings** · 04-13-2008

Originally Posted by SyntheticShield

You know, I have given some thought to that before. My thinking was that if everyone uses a 3" exhaust, then why not run two 1.5" or 1.75" pipes?

With a 3" exhaust pipe, you get about 7" squared of cross sectional area. With two 1.75" pipes you get about 5" squared of cross-sectional area (total).

It's better to have one pipe.

The gains to be had simply aren't there to run true duals on these cars. Catbacks are available that flow very well even for the fastest W-bodies. And the sound won't really be that different...

**N3p** · 04-13-2008

I don't know much about it, but from what I've heard it's not a good idea at all to run a true dual on a GTP. There's a lot more to it than you think (couldn't tell you what there is but I've heard people talk about it before). I'd ask around more before doing it.

**VinnieGTP** · 04-13-2008

The front o2 is your only REAL enemy. Figure out how to get it to read both banks and you're golden. Zooomer is the only one to date, that I know if, to do it. That was also like 6 years ago.

**whitcomb** · 04-14-2008

yea thats the only problem im runnin into right now is the o2's

**Fish** · 04-14-2008

Its really not worth it IMO. All you are doing is adding weight and work to get correct O2 readings and for what?? A very small notice in sound?? Swapping to a different muffler would net you better and be alot cheaper.

**BackInBlack** · 04-14-2008

Do the L36 F-bodies run true dual? What about a summation box? A device like that might allow you to plug both o2 sensors into it, and the box's output would be fed to the PCM. How about scrapping the post-cat o2 sensor, and using the input (with a modified PCM code) and re-locating it to the other bank? How about Corvettes and Mustangs that use a true dual exhaust?

**Sinister Drag Designs** · 04-14-2008

Mj(Fair muffler in LaGrange,Il) and I had been working on a true dual exhaust setup based on ported manifolds(removal of the stock crossover) and pacesetter headers.
o2s were the main issue we were trying to tackle. A true x-pipe setup with the o2 in the center seemed to be the best solution.
The only thing that stopped us was the location of the x-pipe. Having your o2sensor reading from how far away the "X" section needed to be to fit was not an ideal location for proper readings.
With How pacesetters use a y-pipe to focus the o2 reading it seems that this would be the best solution. Pacesetters seem to be the only Headers on the market the get true readings from both banks. We have not tested Intense's old "BIG Dog" headers. SLPs and TOGs give the illusion that you are getting both banks read but that is not the case. If you see the inside of them and understand how exhaust flow is merged when put into collector of that kind you will see my point. S&S read from the front bank only but are not that hard to correct. If a few small things were fixed on the S&S they would be my next choice.

hope this helps, if you are able to make somthing along the lines of true duals keep us updated.

**Fish** · 04-14-2008

Originally Posted by BackInBlack

Do the L36 F-bodies run true dual? What about a summation box? A device like that might allow you to plug both o2 sensors into it, and the box's output would be fed to the PCM. How about scrapping the post-cat o2 sensor, and using the input (with a modified PCM code) and re-locating it to the other bank? How about Corvettes and Mustangs that use a true dual exhaust?

Negative. Hell, even LS1 Fbodies do not run true dual. They go into a Y from the manifolds/headers. Go to a single muffler that has two outlets.

I dont understand why a true dual setup. The gain VS loss doesnt add up to me. Hell, I stuck with my Regal single out while everyone is jumping on the GTP catback/ SLP dual bumper slit combo. Weight savings.

**Coogles** · 04-15-2008

Originally Posted by Fish

Negative. Hell, even LS1 Fbodies do not run true dual. They go into a Y from the manifolds/headers. Go to a single muffler that has two outlets.

I dont understand why a true dual setup. The gain VS loss doesnt add up to me. Hell, I stuck with my Regal single out while everyone is jumping on the GTP catback/ SLP dual bumper slit combo. Weight savings.

No kidding. I never understood why anyone would want to add a second muffler to a Regal. The added weight plus extra expense of buying another muffler and cutting out the bumper, the extra hangers...it'd all be a big pain just to have an extra exhaust tip coming out of the back. Single exhaust on the Regal FTW.