I agree with pvlexxus, I have done that on my CLk 500 and gets up. It seems breath better.
Oh, sounds bad ***

 

Glad it worked out well for you . It may continue to change in note & performance slightly over the coming weeks. Anytime you change exhaust components it takes a while for the full effect to kick in. High flow 2nd cats (and 2nd cat delete and/or xpipe if possible) are the best bang per buck mods on the V8s simply b/c it costs so little to do and are relatively easy to install.

Congrats & enjoy

 

I just had 2nd cats deleted yesterday and replaced with straight pipes. It sounds awsome as I expected. Check out the link below. It costs $160 at local muffler shop.

 

I have a question what Resonator Removal?
that Resonator Removal has to be removed? the two finish having chrome queues? the Center more small? all? Thank you! and sorry for my English

 

hello,
I have a 2003 SL500. I have been going over threads on here for weeks. getting all different anwers. I would really appreciate your input. So do I remove the rear cats or the end mufflers right before the tips?
thank you in advance for your help .
Ray

 

help I am torn and don't want to go in the wrong direction. You just removed the rear mufflers correct? any sound clips? I have a 2003 sl500 and am not sure Muffler delete or sec. res. delete?
Thank you

 

OK, it's been a bit since the last thread update, so I'll add my 2 cents.

1) I just had the secondary cats deleted (The 2 cans that just about line up with your door handles, not the resonators back at the exhaust tips) and 2 straight pipes installed. My pipes are the same size as the rest of the exhaust - 2.5")

2) There is slightly more grunt in the 2000-4000 rpm range. Best guestimate, only about 2db over stock. Pretty much un-noticeable.

3) When At about 25% throttle in the 2000-4000 rpm range, you'll notice a bit more pep. The engine breathes more freely and when you go from 25% to 50% throttle you'll accelerate quicker than stock with a more instantaneous response. If you go from 25% to 75% or Wide open 100% throttle, you'll experience a noticeable increase in acceleration over stock. There will also be about a 10-15% increase in 'growl' sound in the 50% throttle plus range. The car basically sounds exactly like an SL55 @ above 50% throttle.

4) Prior to removal of the 2nd cats, I was getting consistently between 11.8 - 13.1 mpg in City driving, and between 23.1 - 25.2 mpg on the highway. After the removal of the secondary cats, I'm now getting a consistent 14.2 - 15.1 mpg in City driving, and 25.8 - 27.2 mpg on the highway. My combined average is up from 14.3 mpg to 16.7 mpg and that's even with slightly more aggressive driving with the new state of more pep.


5) Prices for most services here in Seattle are higher than the nationwide average. I paid $240 in Sept 2017 for the deletes, and that was at the only shop I could find that would do the delete. Every other shop would only agree to either stock replacements, or <Magna-flows, Eastern, Walker, or FlowMasters> Universals @$400-$600 over what I paid for the deletes. So I got superior sound <same as stock at cruise and more growl under hard acceleration>, better performance, and increased MPG's for under 1/3rd of the price of more restrictive universal cat replacements that are due to fail again within 60-100,000 miles. I'm EXTREMELY happy with the secondary deletes and would wholeheartedly suggest it to anyone thinking about it.

6) Those wondering about passing smog. If you live in a state that does Smog via your OBDII port (The Majority) there are no issues passing since the secondary cats are unmonitored. If you re in one of the few states that still uses a sniffer, the news is still good as the primary cat's flow at about 320, and that's well above the 190 necessary to pass the EPA mandate. So the 2 primary cats' are far more than what's necessary to be EPA compliant.



***** Update regarding low end performance:

a) From a standstill, throttle response in the 1100-2000 rpm range at 25% Throttle will be slightly less than stock. To get the stock response from a standstill requires about 50% throttle as opposed to 25%.

b) From a standstill, 50% plus throttle off the line will pull harder than stock, and 75% to WOT will pull significantly harder. So while below 50% throttle will be a bit slower until you get to 2000 rpms, if you hammer it from a standstill it'll accelerate more aggressively.

c) If you are at hwy cruising speed at about 2000 rpms @ 25% Throttle, and gradually increase throttle, you'll accelerate at a slightly faster rate than stock. If doing the same at cruising speed and you drop the hammer from 75% to WOT, then you'll set off the ESP as the car just launches itself towards top speed without any restriction. It's in this specific instance that it seems like a completely different beast. The RPM's increase at such a rapid rate that the increase in acceleration is VERY NOTICEABLE! 65mph to 130 mph happens in the blink of an eye compared to stock.

 

Thanks Aussiesuede and the others above, I think I will have this done next week on the 2009 SL550 I just picked up recently. It seems almost like a No Brainer, any comments?

 

 

 

PM Sent

 

yes, where did you get your work done Aussie? I just picked up an 09 e63. thanks!

 

So No Secondary Cats Anymore 2003 SL500

well after having a secondary converter honeycomb break at 32000 miles and the fact that an SL needs more bark i decided to remove them instead of replace cat.
results ...
idle ... just a touch of difference from OEM configuration
highway speeds over drive can't really tell much difference

BUT 2000 RPMS + ... fantastic and shifting up through the gears will bring a smile to any ones face
I did upgrade air filters to high performance dry filters help with better air intake
DO it now if you haven't but good luck finding a shop to do it, had to do it myself, and will eventually have pipes welded currently stainless clamps

 

This statement is false ^.
There is little to no advantage other than pure guttural noise. It's OK to say you want more noise. as an owner, personal choice is all that matters. It's a cheap way of making it louder. Not faster or more powerful just louder. As a matter of fact, there's a high probability it'll diminish low end torque with a factory ECU settings. Factory cars are designed for optimum performance with the restriction of those cats. Take that away and exhaust speed (velocity)slows down meaning you don't cleanly evacuate the cylinder as much as with them. Even McLaren's have secondary cats and they perform and sound very nice
Anyone with a 500 or 550 would be well advised to remove/replace the very restrictive factory X pipe if you want a "small" improvement in power