Hi all,

Had my SL55 exhaust modified yestrerday, bloody hell my car is loud now!

In basic we chopped out the secondary cats and resenator boxes and replaced it with straight pipe, please see below (excuse the mobile phone picture!):



A few questions!

1) We didn't do an H pipe or X pipe, both banks are separated through the entire system. Each side does not meet at any point unlike before where there were 2-3 H Pipes. I can here it slightly pulsing through each side of the exhaust system, would it be worth installing an H pipe or X pipe to connect the two parts together, would this help to mix the exhaust gasses a little better helping performance? What are the pro's and con's?

2) It sounds, as you would expect, bloody awsome! It has developed a very strange metallic sound at low RPM's though. It sounds like a clamp has come loose so it's shaking on the exhaust but everything is tight! It only does it after hard hard driving, I can cruise around for ages with no noise, give it a blast, then when I slow down it starts doing it?

If nothing is loose or touching is it possible that I've destroyed the baffles in the rear mufflers, from the added exhaust pressure? Thus when it gets really hot they start to make strange noises? The noise is really metallic and high pitched, any ideas? Kinda reverberates at low speed!

3) Gonna remove the mufflers next week and replace them with straight pipes using the original tail pipes so it looks stock. Think it's going to sound completely rediculous but will love it Eventually will remove primary cars and get a better set of manifolds.

Anyhow if someone could advise me on the above that would be great as the noise is driving me mad! Didn't noticed much performance loss or gain, maybe a bit of low end torque lost for a bit more up top gained.

Cheers all,

Toby

 

Glad you took my advice RE the X over by the secondary cats.

 

What do you mean buddy?

Also think the noise is something loose lol will check it out tomorrow.

T

 

I bet it sounds menacing!

I think it'll sound absolutely insane without the mufflers.

 

We need some vids so we can hear this beast!

I can't tell from the picture, but did you remove the "H" pipe upstream from the secondaries (158)? it is called "b mixing area" in the diagram.

 

ViDeOs!!!

 

Here is mine with shorty headers and secondary deletes. You can hear the screaming SC thanks to the 180 counter pulley.

http://www.youtube.com/watch?v=wd3Tfq2JlG0
http://www.youtube.com/watch?v=Xi5oI-qNApM

It is actually quite a bit louder than the cheap little flip recorded.

 

@ Chris-W - What did you mean buddy? Have I missed something? Do you think I need an X pipe near where the secondary cars used to be? If you could clarify that would be grand. I can feel it pulsing and the idle sticks a for a short amount when backing off the throttle so maybe it is needed to ensure the gases mix? Let me know

@ Benzo - Yeah it's pretty mad, much louder than other videos I've heard where seconday cats & resenators have been removed

@ cal1 - Yeah will get some videos done shortly. Your sounds lovely, but quite a bit quieter for some reason? Maybe just the audio quality.

As per the diagram, yes the H pipe (B mixing area) has been removed. Each side does not meet at any point, is this the wrong way to do it? My exhaust man did say he could put in a H pipe or X pipe at a later date to help mix the gases a little. Do I need to do this to get better performance, you can hear it pulsing as I'm guessing it's not equal on both sides hence the exhaust sides need to meet at some point?

Let me know your thoughts guys, just want to know which route is best.

Thanks,

T

 

The B mixing area was removed on my last SL55 and it added a much more brutal V8 sound and I didnt have any pulsing issues.

Currently I'm running the Kleeman manifolds and have removed the primary cats. I'll be removing my rear resonators when I'm back in a few weeks too. Toby where is your exhaust guy? and is he expensive?

 

I'm sure an x pipe would make it sound better. Just go ask the e55 guys.

 

Hey Chirs, just sent you a text. He's based in Brixton and charged me £350.00 for the work. Been using him here for years really good guy in all honesty.

Thanks for the offer on the pump but went for a Johnson in the end

 

I would not delete the mufflers. What sounds awesome on the SL600/65 will not translate into something you can live with on an SL55. The cabin noise would be skull crushing.

I understand lots of us like loud cars (myself included). What would be awesome for a few weeks would quickly turn to not so awesome. In this case I would recommend looking into electronic cutouts. You can be as loud as you want and the moment you get sick of it. All you have to do is flick the switch.

Quick Time Performance (QTP) makes a low profile electronic cutout system its under $400 w/ overnight shippng from Summit Racing. I would highly suggest you look into this option than deleting the whole muffler system.

As for X-pipes or H-pipes. I feel its never a bad thing to merge the gases from one bank to another (after the o2's) However since you don't have headers (I think) Its not really worth it. If you have long headers and cat deletes an X-pipe would help scavenging, but if you got factory primary cats and no headers. Its not worth it. On that regard I think you did the right thing.

Anyways, you have a ton of room to work in some cutouts, with a good turn down. I would put them int he resonator's old location.

My vote is for cutouts and no muffler delete. Best of both worlds.

 

The QTP cutout looks like a great idea. Would teh correct location for this be in the bend just before the center muffler (159)?

 

Best set up for 55k ... shorty headers x pipe and aftermarket exhaust...

anything else is massive drone and just unpleasant