Muffler / Exhaust

[JoFotoz]

I sold Blacksambo a virtually new OEM exhaust ....

I was talking to our Isuzu guru Jerry Lemond last summer, who mentioned the strong possibility that our mufflers have a warm-up valve inside. But he couldn't confirm it...nor could this forum.

If there were one...and it were stuck, it might explain an obstruction severe enough to cause a pronounced improvement.

???

....Maybe can cut up his old one...and check out the "valve" ??

Jo

[blacksambo]

Sorry, I through it away. But, I have noticed when loose it rattles like something is loose inside. Hope this helps.

[Leon R]

So... In 14 years of existence of these cars no one cut-up a stock muffler?

To truly "feel" power increase, most "normal" drivers need at least 10% of extra power or 20hp in this case. Unless you had a clogged system, you wouldn't see that from a simple muffler swap. A clogged CAT could cause this, but not a muffler.

Also, if you have a significant enough blockage in your exhaust to "feel it", you should see it in your fuel consumption.

[evillecutter]

is this mythical warm up valve supposed to be inside of the muffler or exhaust pipe? my muffler has a rattle when i rev up the engine and im going to get a new one (non oem) - if noone knows ill save my old exhaust and get to it sawzall style then let you know what i find

[blacksambo]

Thanks. We're all curious.

[JMNY]

Not sure exactly what the difference was but they changed my muffler,the extension of the exhaust after the muffler and a new chrome tip. It was done by a performance muffler shop called Mufflex here in NJ. I wish I drove another VX recently to really understand the difference but for me it feels completely different. Definitely more horsepower and general flow. I am really happy with the increased performance and sound. I actually called the shop afterwards to thank them for the work and explained the difference and he said it should different but not be that much different. But he did say there may have been something clogged becuase our mufflers were actually encased and maybe there was something wrong in the interior .... but there would definetly be an increase in horsepower. He was happy that I noticed such a difference.

Not sure if it was possible.....but I love my Killer Bee even more

[89Vette]

is this mythical warm up valve supposed to be inside of the muffler or exhaust pipe? my muffler has a rattle when i rev up the engine and im going to get a new one (non oem) - if noone knows ill save my old exhaust and get to it sawzall style then let you know what i find

I just asked Jerry again. He said inside the muffler. And, for sure, the 98 and up Troopers had this "feature". It was supposed to help hold heat in the exhaust and help warm up the cats faster.

Kinda makes it sound like the same kind of thing as the Dynomax VT muffler -- expect the reasons for the valve are different (warm-up vs sound control).

[Leon R]

If VX has such feature, then it would be illegal to install ANY muffler, other than OEM. Because such swap would temper with actual emissions system... Why would Isuzu condemn their customer to such restriction?

But in a real world, no one is ever this strict (or educated) about emissions

Getting back to this "feature", if there is such mechanical devise, I can see how its malfunction could cause a major power (or fuel economy) reduction.

[blacksambo]

Smart!

[evillecutter]

got a new "turbo" muffler installed and it sounds great ($75) - i told them i didnt want anything too loud and he said it def wasnt enough engine for flowmasters so they put one on that they said they use when someone comes in with a v6 mustang and want it to sound like a gt - cut up the old stock muffler with the sawzall and i think i might have found the mystery valve but not exactly sure how it works - ill take pics this weekend and put them up next week

side note: the stock muffler is a behemoth - very heavy - but i was surprised at how clean it was inside after 12 years

[evillecutter]

the side with the valve is towards the front of the vehicle

[Leon R]

Fascinating! So what makes that valve open/close? The volume of the exhaust gas flow?

And is that the maximum amount that it can open?

Thanks for cutting it up!

[89Vette]

I'm baffled by the valve too. (Get it? baffled? LOL)

It's difficult-to-impossible to determine flow path and what that doo-dad really does. I also wonder if it's really a direct obstacle to the "main flow path"...or something in a "secondary circuit"?

[cheetah2390]

After reading through this thread and seeing the innards of the stock muffler, I decided to replace mine. I went with Magnaflow #11225. Had it installed last week for $111 (muffler and labor) at Modern Automotive Performance (employee pricing bc my brother works there). I’ve had it on for about 300 miles. It’s mellowed out a bit, kinda loud if I step on it. Not much if any increase in HP. I will report back on MPG.

[89Vette]

I'm also making a switch. SpinTech makes a 16" [body] offset inlet, dual outlet muffler. I ordered it in the quietest version. (Sportsman XLP)

My shop is going to add resonators before the stainless/chrome tips. They'll point straight rearward vs. being angled down like factory.

Hopefully, I won't regret the change in sound! Hoping for a big of responsiveness out of the deal. Maybe another mpg too.