Coupe King Stainless Exhaust Refinement

[E9Wayne]

Hi guys, I've posted a new thread on this. After several months of research, I was at a Virginia custom exhaust place to show them my set up. They thought Eric's works was exceptional in many respects and had few ideas to tame the decibels and add a little more sophistication to the sound. After weighing some different options for the center resonator and rear muffler, which were much more drastic, they suggested a simple Magnaflow performance catalytic convertor between the down tubes and center resonator. At first, I was totally against this, but they told me I would not see a performance difference or added backpressure. But they persuaded me and cut out about ten inches of stainless pipe and inserted/welded the pictured part for $300 (Magnaflow #51356). I've got less than a 100 miles on the new part, but I already like the improvement and I don't notice any seat of pant setbacks. The sound is slighly quieter and a little mellow but still could not be mistaken for a Coupe King stainless system. The best part is when you get off the gas there's much more discipline versus minor post combustion antics. The shop told me it should mellow overall a little more as it breaks in over the next few hundred miles.

At this point, my exhaust system research is done and I like the results, although someday I may still go the Sven direction

 

[scottevest]

That is really helpful. I have a coupe king exhaust and I love the sporty sound of it but it could be a few dB lower. Love to see a video or perhaps just the microphone from your iPhone uploaded to dropbox with a wav file to compare

 

[teahead]

Cleans the air too!

 

[autokunst]

Thanks for posting, Wayne. I think I would have been as against it as you. But if it "matured" the sound while still retaining the CK sound - AND- scrubs the exhaust a bit... Sounds like it might be a well rounded addition that would compliment the exhaust system. Would love to hear a sound bite.

 

[E9Wayne]

Guys, I thought you would ask for that. I'll try to record some audio next weekend when my wife is back in town.

 

[Sven]

Wayne,

I have a 9" Magnaflow catalytic converter 53006 on mine too. Maybe that is why it sounds quieter than the CK's system. I didn't think the slightly larger rear muffler (5x8x24 #12286) alone would have made that much difference compared to the CK 6" round. The cats get really hot, so a heat shield might be a good idea.

 

[E9Wayne]

Hey Sven, thanks for this advice and my appologies for not reading your extensive earlier post on this subject. My next step, after giving the new CAT about 500 miles, will be to swap rear mufflers for yours. Summit racing offers them for $109 and the install at the same place I went for the CAT should not be much. Your muffler appears to offer more baffling for reduced sound and I'm guessing I'd get more back pressure as a result, but I can always retune Megasquirt I guess.

 

[Stan]

Did you fabricate the heat shield?

 

[E9Wayne]

Hi Stan, not yet. I will play things by ear for a week or two and maybe have that done when I potentially go back to that shop for the rear muffler swap. I do recall seeing quite a bit of space between the new cat and area above it, but the shield is probably the correct thing to do to prevent any issues down the road. After listening to the new sounds after several drives, I'm now convinced the sound change is much less than I originally thought but there is clear improvement in the sound transition between shifts and off the throttle on hard acceleration...she is much more mild mannered now. Sven's rear muffler is the biggest change in sound, I'm guessing...

 

[Stan]

12 years later I still have the stock system VSR installed when I brought the coupe home.
Two years ago, painted the whole thing with Por-15 muffler paint. Still looks new
I have a penny jar collecting cash for SS upgrade but do not want to rush it

 

[Sven]

Stan - yes, I made that from some aluminum sheet. Rivets hold it to tabs welded to the ends of the muffler & cat. with about 1/2" of space between shield & cat.

There is not a lot of clearance to the driveshaft & center bearing above the shield though - sometimes none...

 

[deQuincey]

12 years later I still have the stock system VSR installed when I brought the coupe home.
Two years ago, painted the whole thing with Por-15 muffler paint. Still looks new
I have a penny jar and collecting cash for SS upgrade but do not want to rush it

please @Stan , SS exhaust is NOT an upgrade, and you know it !

 

[autokunst]

please @Stan , SS exhaust is NOT an upgrade, and you know it !

Hi DeQ. Okay, I'll bite - curious your thoughts behind this comment. I view SS as an upgrade for a few reasons: looks nicer, lasts longer, stays cleaner. I was not original equipment on these cars, true. But is OE on many newer, high end cars. Anyway, I'd love to hear your thoughts on this.

 

[Wladek]

If SS is not an upgrade - so what is?

 

[rsporsche]

i am curious also. do you say that because it is not original

with an improved engine, i think that the restrictive stock exhaust will have too much back pressure and restain the engine output.
if your engine is say stock / stock b35, then i think the stock exhaust is still in the realm of possibility. but once you get to higher compression / more aggressive cam / bigger valves / headers, i think the stock exhaust becomes the limiting factor.

in looking a OCCoupe's coupe ... i think it would be a downgrade to go back to stock exhaust from his Fritzbits SS exhaust.

 

[deQuincey]

Hi DeQ. Okay, I'll bite - curious your thoughts behind this comment. I view SS as an upgrade for a few reasons: looks nicer, lasts longer, stays cleaner. I was not original equipment on these cars, true. But is OE on many newer, high end cars. Anyway, I'd love to hear your thoughts on this.

SS
looks nicer ? not in my opinion, you lack the chrome tip and the contrast between the black tube and the tip, a feature as important as the c-pillar roundel for the personality of the coupe
lasts longer ? yes, if 25 years is not enough for you, SS might be an improvement, but make sure that the SS guarantees the inner weldings too, wally and nelly dont (i requested it) so be aware
stays cleaner ? yes, but the exhaust lays underneath the car, except the tip, and the chrome tip is unbeatable, so no difference for me
and...SS sound can not match the original exhaust sound, never ! SS sounds like a plumber installation...
here you are, that is my point, thank you for asking

.... but once you get to higher compression / more aggressive cam / bigger valves / headers, i think the stock exhaust becomes the limiting factor.t.

...i agree, great english writer Th. deQuincey said: “once a man indulges himself in murder,...”

If SS is not an upgrade - so what is?

in my point of view it is a clear downgrade, but there are other opinions that i respect

 

[teahead]

Rusty exhaust matches the rest of the rust on our e9s

 

[Wladek]

but make sure that the SS guarantees the inner weldings too

What inner weldings you meant?

 

[rsporsche]

SS
...i agree, great english writer Th. deQuincey said: “once a man indulges himself in murder,...”

deQ, you have to understand that my coupe doesn't have its original engine ... i bought it with a 3.5L b34 engine. so i don't have an original to save. it also doesn't have an original exhaust. i am replacing my engine with a SFDon 3.5L euro b34 engine. if there was a stock type exhaust for a much stronger engine that would be something that i would look at.

 

[deQuincey]

look my only point was on @Stan ’s comment about SS being an upgrade, he mentioned that he holds the stock exhaust, he is happy with that exhaust (BTW, that is perfectly sound, it is an exceptional exhaust), well, for him, provided he is comming from the original stock exhaust, the SS will not be an upgrade, he will receive a poorer sound, that is my experience, my point and my comment

it is also only to say that perfectly sensible people with perfectly stock coupes fitted with perfectly stock exhausts do not need the urge to swap to SS as many might read from that comment

obviously, like they say in spanish: “... el gato es mio y melofo como quiero”, which “might” translate as “the cat is mine and i can do what i want with it”