B Feelgood

So I have an SL65 that I've installed a set of catless downpipes on along with a set of 4" intakes. The exhaust sounds better than stock but still isn't terribly exciting with this setup.

Just for the hell of it, I unbolted the stock rear mufflers and drove the car for 10 minutes with just the downpipes installed. At low speeds and during light throttle, it sounds horrible with a very loud gurgling/mechanical sound (not a good one). However, at more than 30% throttle, WOT, and full throttle it sounds great and had the perfect volume. It's still not ear shattering (which I wouldn't want it any louder), as the intakes can still be heard over the exhaust at full chap with just the downpipes.

So I ended up buying 3 different universal mufflers and had the intention of replacing the stock rear mufflers with a universal 3" muffler (Borla XR1 both oval and bullet style 12" and 16" and a Vibrant 12" resonator). I took all three to an exhaust shop that does tig welding and the guy just didn't seem to really want to do it. He claimed that the three mufflers I brought wouldn't do much of anything and kept pushing for me to modify the stock mufflers instead. He suggested cutting up the stock mufflers, remove the packing, and put a sleeve over 3/4 of the pipe inside. In my mind this sounds just like straight piping the muffler and doesn't make much sense.

In short, what are the guys with catless downpipes doing for the rest of the exhaust? Am I on the right track with wanting to install a straight through muffler or resonator in place of the stock muffler to get a deeper/fuller sound whilst also quieting down the part throttle noises?

B Feelgood

Here's what it sounds like with just the catless downpipes "rear mufflers disconnected" and 4" intakes.

euphoriaDSM

I run catless downpipes and no mufflers with a h pipe and it sounds perfect and constantly get people saying how good it sounds.

B Feelgood

Thanks for chiming in. Did you make a new h-pipe or are you referring to the h-pipe that's already built into the stock exhaust?

I was running open downpipes with no mufflers just to test it for 20 minutes after the install and it was obnoxious inside the cabin with drone and resonance. This was obviously due to the exhaust dumping out under the middle of the car but it also sounded like a really old diesel truck at low RPM's and very light throttle. As soon as the the throttle is pressed more than 30%, the bad/annoying noises go away and it sounds good. Volume during WOT is also good.

Im just looking to clean up or tone down that light throttle (under 30%) with a set of straight through mufflers or bullet resonators. Do you also find this light throttle noise to be a problem with yours?

cocobeex

same with V8

I have catless Downpipe and muffler deleted.
It sounds like truck when its at low RPM.

I am also wondering, what can I do to get rid of that Truck sound at low rpm

RaceHorse

Everyone has their preference for sound but the "H" pipe stock or aftermarket (even a "X" pipe) will help smooth out the pulsing tone by mixing exhaust from both cylinder banks. I run catless downpipes with stock mufflers in place and for me its loud enough. It allows me to fly under the radar under normal load with the wife and kids and it means business under WOT. Cold start ups are loud and gurgly. There are a lot of cars louder than the V12TTs that are slow. If I were you I'd focus on making it faster and surprise people who are louder.

B Feelgood

Thanks for the thoughts RaceHorse! I can appreciate your feelings on the exhaust sound and level but I am on the other side of the fence. This car only gets driven 2-3 times a week as a second car with no family or discerning other to worry about. Going incredibly fast is only half of the experience for me. I need to hear that amazing V12 twin turbo engine working and that exhaust wailing to really get my heart pumping. If it was a daily driver or if I had family to cart around, it'd be a different story. I already have catless downpipes, 4" intakes, billet diverter valves, 20" wheels, Renntech heat exchanger / intercooler pump, and an ECU/TCU done to the car. I'm probably tapped out on go-fast mods!

RaceHorse

Okay, glad to hear you have the performance mods. My car is a weekend warrior as well. However, from time to time we do a special dinner or get together with it and I try to behave.
As far as exhaust note, I noticed most of the Lambo/ Audi TT kits always have a short exhaust with cross over "X" (mostly because of the rear engine location). If I were you I'd see if it's possible to keep the stock exhaust up to the cross over then straight pipe out the sides just in front of the back tires. The outlets not being under the car should minimize drone. By being closer to the driver and passenger with a shorter run of pipe may give a real unique sound. I realize it might not be that easy without being super low, but maybe just what you are looking for if you can make it work.

euphoriaDSM

Catless down pipes to factory piping with mufflers cut out and tips welded back on. Perfect.

AMG-Driver

I have the same opinion like Race Horse. Keep your eyes on make the car faster.

You will never make a "Screamer" out of the low-reving Mercedes V12, a little bit louder o.k., but in my opinion the engine sounds like it sounds.

Without muffler it sounds too much "ricer" for my taste , at least in the low revs... ;-))

What is strange is, that the V12 N/A Mercedes in the Pagani Zonda SOUNDS REALLY WELL, real screaming, high reving car - but I think it also has another crankshaft firing angle - don't know the english word for this.

BlownV8

My 600's exhaust sounds like the Zonda but with more turbo sounds. It's wide open except the metal cell cats. It sounds amazing. I often drive around with the music turned off just to listen to the exhaust and turbos.

V12TTenthusiast

You could just do cut outs and don't have to worry about picking to stick with muffler deletes or not. I run a full 3 inch mandrel bent exhaust with catless down pipes. I do love the sound of the cutouts open but sometimes the car is too loud for me or I don't want to want up my neighbors since I drive my 65 as a daily so I close the cutouts.

Also since I live in DC and travel to NYC alot, both have some areas where they enforce loud exhaust. Cut outs also saved me from a few tickets. I was 1/4 mile away from a state trooper in MD one time at night and he started chasing me when I made a right turn with WOT and wasn't speeding, saw the lights 1/4 miles away, got on an on ramp, and closed the cut outs at the same time, by the time he caught up to me I was just cruising with the cut outs closed, he tailed me for 2 mins maybe to see if I didn't notice him or if he was going to see if I was going to speed but then gave up and left me alone lol.

AMG-Driver

Do you have a sound example of your car? Would be interesting...

Here is also a good sounding N/A V12 Mercedes - The CLK-GTR AMG race car from 1998. I saw this car on the Nürburgring "live" years ago and it was very impressive, so fast and very smooth...

Look in the video from 0:00 - 0:30 behind this is too much music in the video...

euphoriaDSM

failed post

wlelandj

I have catless downpipes with this Gibson SS dual 3/3 muffler with internal x-pipe. It sounds pretty good. There is a bit of highway drone, but not too bad. The wife doesn't like it, however. Looking into some Vibrant resonators to keep the peace.
-Leland
http://gibsonperformance.com/i-22731...s-55114s.html#!

Ch Mike

I have an 04 SL600 speedriven catless downpipes, cut off thr mufflers, used my old downpipes to make pipes to replace the mufflers and welded the stock tips back on, if exhaust is dumping under your car it will drone u must have it exit out heres some videos

https://m.facebook.com/story.php?story_fbid=10210954425754878&id=11806338 66

this was with the rear pipes dumping right before where the mufflers where...


here the tips have been welded back on
slight truck sound at idle lol but its not too bad the turbos are louder now too im pretty happy with the end results

DUDMD

First start up of catless downpipes and I believe the mufflers were previously gutted out by previous owner, I see cut and weld marks on them.


and on the dyno, clearly her it through the entire range on warm engine.

Inside the car with top down:

Ekselent

Amazing sound .... I think this engine is the 6L naturally aspirated engine.

StirlingMoss722

Pagani = Flat Crank.