Just cut the secondary cats, our cars don't have resonators.

i think about 99% of people who have cut the cats, myself included, have been very satisfied with the results

Hi all,

Thank you for this thread. I just picked up my GTS and am looking to start customizing it. 3 questions:

1- Will removing the secondary throw any codes?
2- If the dealership sees this, will it void my warranty
3- What kind of shop am i looking for to do this? I'm in the Dallas area. Can any upgrade shop do this or do I need to hit a welding place?

Sorry if the questions sound stupid. I've had many sports cars but have never done a cat delete.

The questions are stupid because the entire thread is about your questions.

So I'm assuming your anger stems from being molested as a child??? Maybe some meditation would help you.

1) no codes, sensor up stream.
2) not sure about warranty, depends allot on dealer.
3) would be best go to a custom shop , anybody can cut out and weld in a fence post. We pay big bucks for these cars , get a high quality shop who will do a nice job.
4) this mod totally transforms the car.

I appreciate the info!

If this has been covered, I apologize. It's a pretty long thread and I didn't see it addressed. I love the car! Tied with my 996 GT3 as my favorite one so far. Can't wait to get it on the track.

S...

just want to point out that the dealership CAN'T void a warranty. What they can do is flag the car as modified which means that they will always do their best to link a failure back to your modification prior to doing any work. They would likely do that for a decatted car or perhaps a tune being detected. But it doesn't void it altogether.

Lucky for all of us that 'tinker' the Magnuson Moss Warranty Act exists for this kind of stuff. The burden of proof is always on the manufacture to link the modification to a failure. For example, if you have a seat belt failure or a command system failure, it's not likely that deleting your secondary cats are the cause so the warranty stays intact. Fail emissions testing or throw a check engine light and things get more complicated for you,

Bottom line; don't be afraid of doing these low impact modifications for fear of your warranty being void.

Thank you Skilly! Good to know. From reading the forum, I'm going to make an effort to get to know the service manager as well just in case!

one very important caveat - this is protection under US law....I should have mentioned that!

Yep.... Good to know for sure.

I'm concerned for their thoughts on mods. When I asked about doing an ECU rear wing delete, my advisor told me they really can't do anything like that. Maybe I just need to get to know them better.

They dont code things like that - you need an indie shop to do that or purchasing the bypass product that one of the forum member sells (FAR cheaper than a shop day). I think that they do this because your VIN has a specific build related to it and they don't adjust it once the car is 'born' except through standard updates across the fleet. Even parts, unless you have a specific part numbers, are always looked up against the VIN and the way that it left the factory.

Do these two mods, the EVM and removal of secondary cats "stack" so to speak? That is do the two mods combine for an even louder overall exhaust note?

Which of the two mods make the largest change in sound?

Can I assume the conversations in this thread about cat removal apply to all version of the GT? I'm seeing references to the GTS but I have a GTC.

Thanks

I agree with everything Tinknocker said except #4 that this will totally transform the car.

Yes!

You have to be molested as a child? Great reference for my comment *** hat.

If you want to learn about your car spend the time reading the threads.

Your experience on these forums can only be made better by putting both thecutter64 and AMG 17GT on your ignore list. There's a reason AMG17GT was one of the few folks on the Private Lounge to have a negative reputation score.

Who are you? Defending a guy that makes child molestation comments?

private lounge?

In my opinion AMG 17GT, you're just an angry maladjusted troll that likes to make himself feel big by attacking legitimate questions. That's cool. Everyone needs a hobby I guess. Just a shame you had to do it on Thanksgiving. I've been on a number of different forums previously and have encountered people like you. Just mad at the world. Here's an offer.... you don't worry about my posts and I won't pay any attention going forward to yours. Life is too short and there are way too many cool people in this forum from what I've seen so far, with whom I'd like to converse. Deal?

Haha. Yeah man your post was “stupid” all In your own words. All you had to do is spend the time and read a little bit and maybe you would’ve learned something more than you asked. We have all spent a lot of time trying to figure out this car and it’s there for you to learn from.

This forum is great. Made many friends over the last 15 years and Tracked cars with many members. Maybe you should check your own attitude and “molestation” references.

Want to add a couple of comments that point back to a few recent posts.

First, Magnuson Moss Act - MM came about because manufacturers used to deny all warranty coverage to a product they built that the owner modified. Modifying a car could be something as simple as changing the wheel/tire sizes to custom aftermarket ones. Then the MFGR would deny ALL coverage, most of which was completely unrelated to changing tire sizes. So, with MM, the MFGR has to prove there is a nexus to the mod and the failure to deny coverage. As an example, if you change the wheels/tires and the driveshaft fails, the mfgr will probably try to argue that the cause of the driveshaft failure resulted from the changes in torque applied to moving parts on the DS thus causing that failure. But, they could not deny, let's say, a broken rearview mirror as a result of that tire/wheel mod.

Now a comment about "aftermarket" tunes - Modifying the Engine Management System (changing data files in the EMS) is a very different story. ALL EMSs are "certified" by the EPA here in the states, and the EPA equivalents in Europe for those cars. If an owner makes ANY change to ANY data files in the EMS, they have essentially decertified that car for emissions requirements, AND have committed a crime in the US. So, for "tunes" as they are called, you have to realize that going in for warranty work can be a very different story and not protected by MM act.

To the question about asking a "dealer" to access the EMS and make changes (and assuming if you "get on the good side" of the SM, maybe they'll slide you a favor under the table), trust this - when they say they have no access to such files, they're telling you the truth. If an ECU needs to be reflashed for any reason, that comes directly from the factory (MFGR), and not some tech in the back room of a dealer. That is, unless he/she has access to "hack SW" or a piggyback device they can mod off the car.

I am an HP Tuner guy and, yes, have committed my share of "crimes". At least I was never in the business and never charged anyone to make data file changes and the owner is ultimately responsible for work they approved to be done to their car.

Just keep in mind there is a separation between aftermarket EMS mods and other mods which the MM Act was designed to protect consumers.

Actually, the MM was largely born from the manufactures tying the warranty to servicing the vehicle. They had built in disclaimers that service, the associated intervals, and the aftermarket parts installed by anyone other than an authorized dealer would void the warranty. Funny that today most of the serviceable parts are supplier sourced (brakes; filters etc). The act was created to fix this problem and in doing so, it allowed leeway for aftermarket parts to expand to include what we see today - a vast market of great choices outside of the manufacturer. And, of course indie shops that perform the work at a fraction of the cost WITHOUT voiding or compromising your warranty.

For tunes, any manufacturer that voids your warranty for a discovered tune is over reaching - Im sure there are cases, but Ive never seen it to that extreme. Instead, they can (and will) tag the car in their system with that tune and decline coverage for that area (for a tune it could be the entire drivetrain) of the warranty, but if something unrelated fails that would otherwise be under warranty it would be covered. Some modifications are actually embraced - great example of this being completely acceptable, even with engine tunes is Dinan - they are a well known BMW tuner that was sold and installed in many BMW Dealerships without ever compromising the warranty.

Dinan is factory authorized and factory certified. They didn't start out that way. Same with some GM and Ford authorized companies such as Calloway and Shelby, but that is different than, let's say Vengeance Tuning which is a mega aftermarket tuner in Atlanta, but NOT factory authorized. I agree, the manufacturers aren't aggressively pursuing aftermarket tunes, one BC the secondary marketing impact on performance helps them sell more cars; two, the MFGR has no legal responsibility to snitch for the EPA; and three, GM, Ford, MB, sell some cars promoted as track cars and warrantied under those situations. EPA stops at that point once the vehicle is off the public roads.

GM, since 2019 on the Corvette ZR1 and now the new C8 and including several other models, has moved to a new (E99) ECU along with their B Architecture which, essentially, is a firewall with a rolling coded access that GM generates making the E99 untouchable by tuners without authorization from GM. GM has announced they will evaluate and provide access (authorize) some third parties who submit proposals and GM accepts. But they'll need to have factory evaluation and approval of the mods used (Like Dinan) and likely, no approvals would be given for a non track or dragstrip dedicated vehicle. But once Calloway build/tunes a car that comes with the obligatory legal notice, track use only, the owner of that car can do what they want and those cars will end up on the street.

Many tunes don't require remapping - Piggybacks or "juice boxes" just Y connect into the sensors and the ECU. Burger, Dinan, Racechip (and others) don't need access to the software or ECU at all. That said, for every clever firewall, a just as clever coder breaks in and ends up mapping them. For example, when Porsche released the 991.1 the Bosch ECU was 'uncrackable'; Cobb had an tune for it about a year later.

Fun Fact - Dinan is not unilaterally accepted or 'certified' by BMW. Only Alipina is a certified BMW Tuner. Instead Dinan lives in the grey area where some of the dealerships resell it and install it and others don't. As a precaution, they carry their own warranty that mirrors the factory warranty should a challenge be registered by a dealership (they are independent and not factory owned/operated).