Correct. I replaced the OEM primary cats with the cats in my signature, didn't need to do anything to clear/prevent CELs.

Thanks for posting - looking at doing a similar setup on my '05. Which Magnaflow cats did you purchase? I've been looking at their web site and it appears there are a number of options, and not sure which specific ones to purchase. Any help you can provide is greatly appreciated. Thanks.

Does anyone know of a good shop either around Charlotte or Asheville area that can do the DT install with high flow cats so I can pass the NC inspections? Any suggestions/recommendations are greatly appreciated.

How long was longest wait time, I am on four months plus ... with no word of a possible date? (still waiting on Cats and Studs too)

I saw they were backordered, but am uncertain as to time-frame. It appears some re-sellers may have the correct ones in stock, but I haven't called to confirm.

What would you think of running the DT long tubes and splicing the Gsport cats in the Y pipe (either custom, DT or URD). Too far downstream to get hot enough to be effective?

That's actually what I'm going to do to mine next.

The install of my headers didn't come out like I hoped it would, so I'm going to order some of the longtubes, already have a replacement DT Y pipe because my original one got hacked to pieces getting it to connect to the cats...

So gonna pull out what's there, install the long tubes, the new DT Ypipe, take it to an exhaust shop and have them install the Cats where the resonators are in the DT ypipe, seal off the O2 bungs and have new ones installed behind the Cats in the new location and extend the wiring harness for the rear o2 sensors.

Will take longer to get up to temp, but should work otherwise.

Burtman Industries

Burtman had a few in stock. I got tired of waiting with I estimate for shipping. Canceled order and bought them from Burtman. They were the ‘premium’ version that is 100% stainless steel. So cost a little extra.

Derek V

I'm definitely interested to see how this turns out. It seems pretty simple for a shop to splice the cats into the DT Y pipe. Quite a bit simpler than trying to attach them to the Shorties and get things to fit properly and mate to the y pipe(which it sounds like was an issue for you).

I'm not sure I care about the O2 sensors enough to move the bungs. I think I'd just do the simulator and trust the new cats are doing the job.

I also like this approach, as it I may be able to do this in stages. Stage 1 - long tubes and simulator. Stage 2 - y pipe with cats.

Also - How does that Vibrant Ultra Quiet resonator work for you? I have a 20" dirty deeds and added the vibrant bottle resonator to tone it down a bit. I'm sure with the headers, I'll need a bit more...

For anyone who has done this with an 2005+, what magnaflow cats should I order? Little hesitant to have the old cats welded on. Thanks

Yup it was. I think the flange that was welded to the collector on the header wasn't welded on very square, and as such kicked the cats all outta line... The Flange that was welded onto the top of the cat to mate to the collector flange was dead nuts on, so it only leaves the collector flange to be outta whack. I wish the installer would have welded them up in a jig that they built off the OEM manifold they took off, but that didn't happen and they made it right by not charging me for their fab time.

Still not 100% happy with the results as one of the exhaust pipes is pretty close to the front driveshaft slip yoke, so I have to keep it pumped full of grease as it cooks out pretty quickly.

Someone has already done roughly this configuration on a GX already which is where I got the idea.

The only difference is they had 100% custom exhaust done from the headers back with the GESi cats, a j-pipe (1/4 wave resonator), and I forget what muffler. There's a post in the GXOR facebook group where Dan goes through his build and even posts some dyno results too.

Not sure if he relocated the rear O2s or not, but I figured I would because I have emissions to worry about here, so I figured I'd give it a shot first. If that doesn't work out, move to the O2 Simulator.

But, I actually found that after the shorties, it actually is a touch quieter than the OEM manifold was. I like the Ultra Quiet Resonator, though. Really helped with the drone of the Magnaflow muffler. It's still there, but not nearly as bad as it was prior.

If I were to do it again, I'd go straight to a 1/4 wave resonator/j pipe and target it for 2100-2200ish RPM.

I'd recommend the Gesi cats I have linked in my signature. They're a bit pricey, but will outlast the truck. With how expensive that job is, buy once, cry once.

I also noticed it SIGNIFICANTLY improved/reduced the "rotten egg" smell under hard acceleration that I had with the OEM cats.

rrcats.com to sell your old cats, and if you sell all 4, you'll get close to recouping the cost for 2 of the 2.5" Gesi cats.

Hey All. New to the forum here. Thanks for all the great info here and all around!

I have the classic header crack in my 'new to me' V8 and I am wondering if anyone has installed the DT Shorty headers and kept everything else stock?

I am not looking for power gains or sound so much as not wanting to waste my money installing OEM headers that will crack again. Ideally the DTs are similarly quiet to the OEM ones when paired with stock cats and exhaust but if anyone here has experince with it I would appreciate your thoughts.

Thanks!

This is the route that many have taken and the intended install method that DT details in their install instructions.

The reason folks upgrade their cats when doing the work isn't for sound, so much as it's about replacing a worn part with one that should work more effectively.

As a note, the DT shorties are quieter than the OEM manifolds.

Thanks for the speedy reply JONBOY345!. Sounds like I will be placing an order for some DTs here. Cant handle that ticking. Just dont want something that would wake up the nighbours or create a droning exhaust note.

I will suggest while you're doing the work, pick up the DT y-pipe as well. I did it before my headers, and I noticed a significant reduction in the number of times the vehicle would downshift on the HWY when using cruise control. The DT y-pipe has a couple of resonators in it to help with keeping drone down.

But, the muffler has the most significant impact on exhaust sound of any of the components we've discussed. As long as you keep the OEM muffler or something similar, you should have no issues with being a nuisance to neighbors.

Even with my set up, headers, aftermarket cats, y-pipe, and Magnaflow Catback, my truck can barely be heard at RPMs that are typical of neighborhood driving and engine loads. It'll make some noise under heavy load, but otherwise it's very tame.