richc63s

Hey Guys,

I'm looking at buying either a RennTech or ASR module for my 2020 C63S Coupe (One of the plug and play modules which keeps the exhaust valves open all the time, normally they only open past a certain RPM, even with exhaust 'on') Just had a couple of concerns which I'm wondering if someone might know about:


- Is there a reason that the valves only open past a certain speed/rpm normally? Is it just for noise regs or is there a mechanical reason?

- Are there any warranty issues for using it? Would it show up on some kind of diagnostic check at a dealer?



If anyone's got any experience with this, let me know!

FLC63s

I have never heard about the valves opening or closing based on RPM.. in different modes, they will either be open or closed, but I dont know of them being dynamic while driving and just opening or closing based on throttle position.
With the RennTech and others, they normally default back to closed when the car is shutoff .. (not 100% of time, but majority)

I have the AWE Switchpath exhaust, and it does it this way..

Never had any issues with dealer, but this also has to do with how picky your dealer is

magno.amg

I have the ASR, my valves are open 100% of the time... They never close. On a stock car, they only open fully at WOT and I believe they are open 80% not ever fully but I may be wrong. They are never opened all the way unless you have the valve module from RennTech, ASR, etc...

FLC63s

do you have Factory Performance exhaust ??

The aftermarket valves are either open or closed .. if using the remote fob...
with the Factory Performance, its possible it is dynamic.. I dont know the answer to that

magno.amg

Yeah I do have the factory performance exhaust. You've heard it

FLC63s

Yes, but I didnt look to see if you had factory switch or fob.

magno.amg

I have both

djprov431

I just installed the Renntech version of this on my 2021 C63S the other day --- get it.

It sounds oh so much better with the valves open 100% however not obnoxious or anything. It's silly simple to install, literally 5 minutes to access the stock plugs and place the module inline and button it all back up -- and absolutely no warranty issues - the module simply operates each solenoid valve in the exhaust (2) -- you can see the valves if you look under the car or into the rectangle shaped exhaust pipes from the rear. When you press the exhaust button in the car (stock) the valves only open 1/4 way -- when in sport / sport + / race you have to get above ~4.5k rpm for the valve to modulate further. Install the Renntech module and it stays open - or press the remote button and it goes back to stock. If you want to remove the module it's 5 mins to return to factory with no issue. It's a no brainer. (note this is all with the upgraded AMG performance exhaust from the factory)

dctwc63s

I might be wrong but I thought that the valves in the mufflers are either open or closed depending on drive mode and its the valve in the h pipe that opens based on rpm.

djprov431

This is easily seen by looking into the exhaust pipe from the rear of the car - and by peaking under the car you can clearly see the solenoid valves and trace the wiring back to the right rear of the trunk. Easy peasy. (I don't know how the H pipe works)

Fordgt40

On my 2018 estate the ASR module made no difference to the sound, later when I checked the performance exhaust does open the valves fully so module couldn’t make any difference.

colek C43

I am selling a lightly used ASR Exhaust Module for facelift cars. I used it on my 2019 C43 for about 6 months and it works well. Message me or text me at 816-678-3545 if interested in buying.

W205C43PFL

@Hibiki in case u r still looking.