15SecDD

2013 CD with 83K miles in awesome condition. Just had the emissions "fix" from original owner when bought in 2019.

I've been running a Rawtek DPF/SCR/Adblue delete with a Malone Stage 2 EGR delete tune since 2019 with stock muffler. Did them both simultaneously. Has anyone with this setup, then added the Cat Delete Downpipe? If so, what are your impressions? Is the OE Cat restrictive? I've heard mixed reports and that's why I didn't opt for a Cat Delete Downpipe originally. I'm looking for more power and more efficiency. More sound wouldn't be bad. I have zero plans to run a muffler delete exhaust.

I also cleaned the intake pipe and intake manifold. Both were 50% clogged. Need to inspect again as I've read the software delete doesn't fix this issue?

My delete and tune impression after 4 years:

- Exhaust note sounds the same as stock. My MKIV Supra Turbo is window rattling loud with a downpipe and exhaust at idle for comparison.

- Exhaust smell went from nothing to choking. I have to turn the HVAC off with windows up when exiting the garage as quickly as possible. I didn't smell or notice anything when stock.

- Power and responsiveness is noticeably improved in the lower and mid rpms. Higher rpms and full throttle appear no different in acceleration than mid rpms with partial throttle. No change from stock. As such, I try to do all acceleration modulating the throttle to prevent downshifts. The high rpm power drop off is disappointing. I'd love to have a boost guage. I didn't drive much long distance when stock to compare, but as is I average 28mpg in the city. On the highway it's an average of high 30s to 40s. I saw a 52mpg average driving 300 miles from Baytown to Dallas this year coming back from TX2K. I was trying my best for efficiency. 😉

- Black smoke and soot! I had zero when stock. Now my entire rear hatch and bumper on my white CD is black after one drive. Greasy and challenging to remove except with soap. Any acceleration at all and I roll coal. Not Cummins coal, but parlor stove nut coal. It's definitely noticeable in the rear view mirror.

- Trans shifting. I keep reading this as an issue post "fix", but my Tip seems to shift great. I rarely if ever put it in sport mode. I would hate for it to hold shifts longer with the new Malone TCU tune. I have had a few concerning shift experiences where something seems wrong, but those I can count on one hand.

So should I add the Rawtek Cat Delete Downpipe? Worth the $$? It's notably more than back in 2019! Worth the time to install? I can't remember how challenging it will be to install DIY. The DPF wasn't hard at all. I've read the O2 sensor bung on the delete pipe is in a stretched location.

Phteven

I have a setup with a catless DP and I quite enjoy it. Exhaust isn't crazy, but it's a diesel so it's never going to sound like a GTS.

For clogging intake/exhaust I'd recommend Cetane/Additive during fillups. A lot of people use Power Service.

It's the same setup as yours (Delete+Malone 2) and I have all the same thoughts as you as far as exhaust cabin smell, soot on the rear/under acceleration.

Gforce1108

My A7 is full turbo back straightpiped. Definitely smells a bit while stopped - nothing while driving. Also malone stage 2. I wish I left the cat for the smell, but it was a good amount more money to go that route (different than the cayenne where you can leave the stock pipe with the cat). It is a bit obnoxious at wide open throttle. I have the delete pipes for the cayenne now and will leave the cat in this case (smell and noise). Prior owner removed the mufflers but it's so quiet the dealer didn't even realize it!

15SecDD

Thanks for the reply. Did you do the cat delete at the same time as the dpf delete or after? I'm curious what the cat delete adds to already having the dpf delete which was noticeable in itself.

Also thank you for reminding me about a diesel fuel additive! I'd been running Opti-Free Summer since I bought the CD, but the bottom fell out of the large bottle I bought beginning of this summer and I sort of forgot about it. That probably explains my decrease in mpg and slight increase in other annoyances like smell. Haven't noticed any lack of power. On the diesel truck forums [Cummins and duramax], they currently rank diesel additives in the following order based on tests. Project Farm did a video as well.

#1 Hot Shot's Secret. This has by far the best reviews and tests. I don't remember it being available years ago when I got the Opti-Free Summer. I'm getting the EDT version with the trick Stabil like measuring bottle at Walmart today since you reminded me. 16oz treats 400 gal vs 80gal for Power Service Diesel Kleen.

#2 Opti-Lube XPD or Summer depending on your climate. Can't find this locally. Looks like they have new bottles that the bottom might not fall off.

#3 Stanadyne Performance Formula.

They rank Power Service Diesel Kleen toward the bottom. Just FYI.

15SecDD

My thoughts for leaving the cat was for smell and potential smoke. I get both with the cat. The cat technically needs to be at service temperature to begin to work and that's probably why I get the noxious fumes upon cold starts in the garage. It's bad. I don't have much a measure for smell while warmed up since I'm driving and out in the open. Maybe the cat is helping then? I don't notice anything from inside the cabin at red lights or already warm idling in a parking lot. You? That would be a deal breaker. I haven't performed a rear end sniff under those conditions. Black smoke is the same upon any acceleration regardless of being warmed up or not or additive or not.

Gforce1108

Very little smoke at startup or normal driving - only on full wide open throttle. With the windows closed I don't notice the smell but I might be used to it! Windows down - yes. I want the cayenne to be a little more civilized

skiahh

Im not an expert, but I suspect the smell and smoke are now there because of the lack of a DPF, not a cat. I think SCR/DEF helps with it some, too, but primarily the DPF.

High RPM power drop off is pretty normal in any car, once you get past the peak. But since diesels have their oomph down low and aren't designed to be high revving engines, that's what you'll get at high RPMs. Want high revs? Get a gasser.

All the "coal" you're rolling is unburnt fuel particles, i.e. wasted fuel. The tune is overfueling when you stomp on it and the unburnt stuff now freely flows out the pipe and, because of the design of an SUV, the air currents and eddy currents pull that up onto your hatch. Does that with regular exhaust, of course, too, not just when it's overfueling. All that stuff you're cleaning out of your intake pipes is now flowing out your exhaust.

Once my warranty expires, I'm getting rid of the EGR system, but keeping the DPF and SCR. I enjoy not having the diesel smell; I can get it all I want in my pre-emissions Cummins Ram.

Offroad_958.2TDI

do all the straight pipes!!!!!!!!!
i have a rawtek stage 2 straight pipe all the way through at 3” I have no so and heavy exhaust smell only the first couple weeks after tune now has more of a MK2 golf tdi smell to the exhaust at idle Which as a diesel lover I rather enjoy its kinda a cross between old 2stroke boat and late 90’s Cummins 12v. Maybe the issue is your tune maybe the overly restrictive exhaust in your pipe causes early cooling in the tail pipe. Driving from Laramie WY to northern Iowa I got 1100miles to a tank on the down hill section. Clean as **** on the back. But also I have a steel bumper on the back. But I love my rawtek tune and pipes but the custom part Makes that thing sound like a Delta Lancia from the 80s. I Drive my cayenne all the time at 100-110 mph and I have seen a huge jump in MPG at that speed from factory 28.2mpg to now 50+ depending on wind. The dirtiest part of my car still is the bugs on the front maybe check out the rawtek tune maybe start adding power service diesel additive or Howe’s diesel treat in the winter. You definitely won’t ever regret the PS crane booster ever. Especially high RPM it’s good for adding up to 5 to 10 miles to gallon depending on the wind.

J3t3r

What is the ´custom part you are referring too’ ?

also, awesome photos !