[OneCleanBMW]

Thanks for the pics/vids. Very helpful. What will removing the secondary cats do? Also, where are the primary cats?

Noob on this topic. I miss the e9x days, change the xpipe and muffler, and you're good to go.

[RugbyBro]

Originally Posted by deeldoo

Just my opinion, but i feel the B58, N55 etc all sound muffled

I actually think this as well - I think it’s really down to exhaust manifold design and the way three cylinder banks collect into two pipes then merge vs a 6 cylinder collects into a single pipe. Case and point, I think that EL S55 sounds more raw & open than N55/B58 and has tonal qualities similar to a GTR VR engines and the 991.2 & 992 C/CS/T engines. Similar thing on Valvetronic’s EL midpipe (currently the only example of an EL S58, but should provide a good basis for the future EL mid pipes that will be released)

[RugbyBro]

Originally Posted by OneCleanBMW

What will removing the secondary cats do?

Make your car louder - this will have the biggest impact on volume without triggering CEL or voiding warranty

[Mr.E46M3]

Thanks for the clip...it does sound SICK!

[Telly9987]

So Im taking my car into my shop and she's going up on the lift for the first time in the AM. Im debating what to remove. Both resonators AND the cats? Just the cats? Just the resonators? X pipe or H pipe? So many options and configurations....

I feel that without cats, and 2 sets of resonators there has to be a dip in performance. Everyone always wants to straight pipe everything and have everything wide open BUT back pressure is here for a reason (by profession I tune race bikes). I see it on my dyno all the time with lack of pressure or too much pressure effects power and mapping should be adjusted. On our teams bikes for the past 2 years we have introduced butterfly flapper valves BACK into our systems with tune-ability to control angle and adjust pressure. EVT is a whole map I focus on with my riders to help with throttle smoothness and responsiveness..

Really torn here....

[RugbyBro]

Originally Posted by Telly9987

So Im taking my car into my shop and she's going up on the lift for the first time in the AM. Im debating what to remove. Both resonators AND the cats? Just the cats? Just the resonators? X pipe or H pipe? So many options and configurations....

I feel that without cats, and 2 sets of resonators there has to be a dip in performance. Everyone always wants to straight pipe everything and have everything wide open BUT back pressure is here for a reason (by profession I tune race bikes). I see it on my dyno all the time with lack of pressure or too much pressure effects power and mapping should be adjusted. On our teams bikes for the past 2 years we have introduced butterfly flapper valves BACK into our systems with tune-ability to control angle and adjust pressure. EVT is a whole map I focus on with my riders to help with throttle smoothness and responsiveness..

Really torn here....

AFAIK losing back pressure is always beneficial, it's the lack of efficient exhaust scavenging & resulting drop in velocity that results in a drop in performance. The turbos/turbines already regulate the "scavenging" needed. For turbos, less back pressure means the turbos can push higher boost if tuned for it - hence why you have to go catless / high-flow cats for higher power when tuning.

You should ask yourself if you like the stock tone. If yes, then try removing the secondary cats - this will add the most volume without introducing much rasp - this may get a bit bass-y though based on experience with S55. If you remove the resonators, then you'll probably want to add an X or H to merge the pulses to fill out the sound and help reduce rasp. As an anecdote, one guaranteed way to make S55 sound worse (yes I said WORSE) is to run unmerged straight pipes back from the cats.

[jonahk]

Is there much of a difference with the exhaust button off? (I.e. can I sneak down my driveway in the morning without waking up my neighbors?)

[hayko_M340]

I remember reading somewhere on the forums that the factory exhaust was a Equal Length. Someone correct me if I'm wrong, sounds great with dual res delete. Still have yet to see someone take off that muffler, can't imagine how much that mufflers holding back on sound. I think that the best outcome for these S58's is all cats deleted + both resonators and just leaving the muffler. Can't wait to see what's to come!

[Ghostriderf80]

Originally Posted by Vic55

I have not but I do know that will add some more interior pleasure.

I didnt drive the car this week but I just opened the garage and did this cold start video... the small cracks are actually loud in person (Cell Vid)

I did turn on all the electronics inside without turning on the engine, hit my M2 button (all agro settings) and then started it which gives the full valve open start.

It sounds like the F80. Someone needs to fix the sound in the aftermarket.

[Bee Pee]

Originally Posted by LBbluem2

What do you think of adding an x pipe in there?

Yes 💯- sounds too raspy to my old 🦻🦻

[VonB]

Subscribed to your channel Vic55, I like it! Stock exhaust is a little bit too quiet for me and exhausts out here in Germany are $4k and up!

[4everkidd]

Originally Posted by LBbluem2

What do you think of adding an x pipe in there?

I would personally go with an H-pipe given my experience with the S55.

Will make the sound deeper rather rather than raspier.

[mike@x-ph.com]

Thank you for sharing OP

For everyone interested in an X-pipe option, we will be offering a full exhaust soon with an X-pipe

[Vic55]

Well first off it was great to read every one's responses, the good, the bad, and the ugly because these are forums and opinions do matter. I am glad it made the front page for more visibility so thank you Bimmerpost once again!!!

I for one wanted to post these videos so any G8X owner could make a better educated decision on what he or she wants to do. I also got some tremendous feedback on the what could be alternatives to the super high rpm rasp. Thankfully the process was easy and cost effective so I can still butcher the underbelly of this amazing vehicle.

I will start a new thread when I get the next surgery done so we can revisit and develop new thoughts and hopefully it gets less raspy up top.

I know a few of you said cut the secondary cats out and I want to but this shop would not touch anything with the word "cat" in it. I am hoping for a true fabricated secondary catless set up like I have on my M8GC. I pulled the resonator there and did a straight pipe with what I think sounds better but of course thats an S63tu V8.

[Graves]

Sounds Fast and Furiousy. Guess I'd have to hear it in person.

[Telly9987]

Put mine up on the rack this am and found a few things....

Why did BMW used mix metal. Half the system is stainless and the other half is a moly bled I believe. The welds are different as well all over the system.... Seems odd

I will be leaving in the 2 cats (for now) and going stainless all the way with an X pipe in the center. Ill see how that sounds and feels then move to an H if desired and then debate removing the cats as well. Stay tuned. Pics coming when work starts.

On a smaller side note, I installed the Clutch Bump Stop and WOW. what a great difference. So much less unnecessary travel past engagement point! Very happy

[vetteflier]

I wish there was a B&B (Billy Boat) exhaust for the M4. The Bullets I had on 2 of my Corvettes had no mufflers, just tuned resonators, and sounded great. The cats and resonators didn't hurt back pressure at all, but gave a terrific sound and probably ~ 10hp. Best of all, they were only around $1300--about $1700 today. 6.2 liter V8s are always going to sound better than any turbocharged 3 liter. But the concept is one I wish would be available. Complete cat back and 304 stainless with full 3" and 4" tip openings.

[vetteflier]

Originally Posted by mike@x-ph.com

Thank you for sharing OP

For everyone interested in an X-pipe option, we will be offering a full exhaust soon with an X-pipe

You sell the VSC-2 valve control. Will they work on a '21 M4 Comp?

[F85MTuNED]

Sounds great and amazing job by your tech it looks like factory..💪🏽

[hellokitty]

It honestly sounds like a F8X now with the added rasp. I never was really bothered by the S55 sound so I like it

[Vic55]

Originally Posted by hellokitty

It honestly sounds like a F8X now with the added rasp. I never was really bothered by the S55 sound so I like it

I did NOT do a good job explaining in my post but some do fixate on the 7k rpms tonal changes *rasp... (parked high rev videos) when actually driving this G80 which most here do not own yet, the actual times one hits red line or close where rasp occurs is just not going to happen unless the driver is that guy that just winds up and down like a fucked up watch- LOL

I still will be doing the X pipe as a public service to the good members here

[SeanWRT]

There is this front page thread showing the secondary cat delete and resonater replaced by X pipe can do. Personally a little loud...and still raspy but less raspy than your car.

https://g80.bimmerpost.com/forums/sh....php?t=1826747

I'd keep the cats and do just the H-Pipe. One step at a time, see what that does for you.