Stoddard/NLA New Stainless Exhaust - Who has installed one?

[Jeffrey Leeds]

John, CJ's post refers to my experiences on July 25, and August 9, 2018 on a chassis dyno located in southeastern Massachusetts. The July pull was done with a GDP twin pipe muffler and the August one with the then new Stoddard. The mufflers were swapped but no other change was made to my Super 90 engine.

My car does not have bumper overiders. When the GDP was first offered I liked the construction and quality but never could figure out an inexpensive way to route the pipes through the cutouts, rather than exiting straight back under the rear valance. I liked the muffler and its sound and quality, but not look of the bare valance "notches." The Stoddard muffler offered the opportunity to revert my car back to having the exhaust pipes exit through the valance notches, and while at it, make back-to-back power comparisons

The results showed that beginning at about 2500 rpm to 4200 the GDP "made" about 1.9 lbs-ft more torque than the Stoddard muffler. At approx 4200 through 4700 rpm the two were essentially equal, and above 4700 rpm the Stoddard muffler improved HP over the GDP to a maximum difference of 1.5 HP at 5200 rpm, where the test was terminated.

After a brief cool-down, a second run was made resulting with the same result. The results were corrected for temperature and humidity, and shop concluded that the Super 90 did-in-fact make 90 HP at peak.

The plan is at some point to spend some more time on the dyno to see if carburetor (Dellortos) and ignition timing changes can be made to improve the mid range dip.

But in end I can say that the differences so small that they are not discernible in regular driving conditions.

Jeff

[Pascal Fillion]

Hi there...I know this is an old post but Im looking for some input if possible. I installed this muffler on my 60 super and I noticed a big POP on deceleration. I checked for leaks with no luck. Ive since brought it to my shop and had them do a complete tune up with valves, timing and carbs and im still getting a pop/ mild backfire on deceleration however, it is better than it was.
My mechanic thinks that thats the way it is with this muffler. Are any of you experiencing this??

Thanks for the help!!!

Pascal

[Jon Paul Phillips]

Hi there...I know this is an old post but Im looking for some input if possible. I installed this muffler on my 60 super and I noticed a big POP on deceleration. I checked for leaks with no luck. Ive since brought it to my shop and had them do a complete tune up with valves, timing and carbs and im still getting a pop/ mild backfire on deceleration however, it is better than it was.
My mechanic thinks that thats the way it is with this muffler. Are any of you experiencing this??

Thanks for the help!!!

Pascal

Hi Pascal,
I had a similar problem .. the flanges where it attaches to the heads are bigger than a stock exhaust, and mine pinched the shroud metal between the exhaust and head causing a leak on #2 and #3. It took me awhile to find it. You might want to check yours.
JP

[Pascal Fillion]

Hi there...I know this is an old post but Im looking for some input if possible. I installed this muffler on my 60 super and I noticed a big POP on deceleration. I checked for leaks with no luck. Ive since brought it to my shop and had them do a complete tune up with valves, timing and carbs and im still getting a pop/ mild backfire on deceleration however, it is better than it was.
My mechanic thinks that thats the way it is with this muffler. Are any of you experiencing this??

Thanks for the help!!!

Pascal

Hi Pascal,
I had a similar problem .. the flanges where it attaches to the heads are bigger than a stock exhaust, and mine pinched the shroud metal between the exhaust and head causing a leak on #2 and #3. It took me awhile to find it. You might want to check yours.
JP

Hi JP,

Guess Ill look into in. Just back it back from shop#2. Although its 100 times better, it still pops on decompression. This shop managed to find a leak on the intake manifold and had it machined. Im getting super frustrated!

[Richard Holler]

CJ
Sounds to me too much like a hopped up VW. The merging of the 2 banks doesn't seem to have helped with the Mid Range Torque! Where most of us use the power,
Are there dyno comparisons? At Idle it sounds lumpy (to me) .
Jay

I'D go with a GDP then, it doesn't sound much different then factory to me and I rather have more torque down low imho, where its more usable in a car like this.

[GregVandenbussche]

Hi Pascal,

Same backfire on mine since i installed it, i don't mind it, the car is rough looking so backfire actually match I think there is a slight exhaust leak where it meets the J tubes as it seems not as a perfect fit. I'm overdue for a detail review as I think some of the weld quality are not up to the price (especially on the collector not debured etc.)

[Jon Paul Phillips]

Hi Pascal,

Same backfire on mine since i installed it, i don't mind it, the car is rough looking so backfire actually match I think there is a slight exhaust leak where it meets the J tubes as it seems not as a perfect fit. I'm overdue for a detail review as I think some of the weld quality are not up to the price (especially on the collector not debured etc.)

I can see questionable welding on mine where the pipes enter the muffler cans on both sides. I don't think they're leaking, but it looks like a matter of time. Disappointing considering the price.

[Dave Wildrick]

I have Zim's M&K stainless muffler clone of the Liestritz muffler on both of my C coupes. No problems with J-pipe fitment (or head fitment) and no leaks or backfires, after suffering through several bouts of trying to make those crappy Danish (Dansk) abortions work. M&K is about the same price as the Stoddard stainless being discussed.

[Craig Richter]

If no leaks are found,, and you still get popping on deceleration, try richening (by turning out) the idle volume screws just a bit. A Lean condition is most likely causing the problem and different exhausts, even if they look quite similar, will have more/less back pressure at various speeds, and often need small adjustments to get rid of any of that "back-off burble". Bad leaks cause big backfires, and if you are having problems sealing at the heads, Summit Racing has big thick exhaust gaskets that might even seal a Dansk!

[Dave Whittick]

The passenger side tail pipe for mine does not align with the cut outs in the rear apron. It's 1 5/8" shy of reaching the proper location. The part was simply made incorrectly. I've been speaking with Stoddard for a couple of months now but have not been able to help. I've also spoken with Magnaflow who weren't able to remake the piece either.

It's pretty frustrating to spend as much as I did for an exhaust that doesn't fit properly. Stoddard will continue to sell them with the incorrect pipe so be warned.

[Mike Wilson]

That's totally unacceptable.

Mike

[David Jones]

Surely it should be a simple fix to make another tail pipe an inch or so longer. I do not understand why Stoddard would not be all over this.

[Dave Whittick]

Surely it should be a simple fix to make another tail pipe an inch or so longer. I do not understand why Stoddard would not be all over this.

I don't know either. They offered to send me a replacement pipe but the ones they checked were only 1/2" longer than what I've got already.

I'm more bothered that they're willing to sell the rest they have in stock no knowing that there's an issue.

[David Jones]

I think I would be tempted to get a local shop to fabricate a replacement and send the bill to Stoddard.

[Dave Whittick]

I think I would be tempted to get a local shop to fabricate a replacement and send the bill to Stoddard.

I've been looking but any shops I've spoken to either don't have the equipment for mandrel bends or don't want small jobs. I've been looking.

In fairness to Stoddard, they said that they would consider a store credit if I sent them the receipt. They did reimburse me when their rear window didn't fit and I had to have it ground down by 3/8".