Anyone Running with NO muffler?

JML79 · April 26, 2005

If so, what do you think? Specifically on the newer model 5.3L V8's? My brother has this set up (2.5in tubing out the back into 4in dia. x 18in long chrome tips) on his new Z-71 and it sounds awesome! Yes, it is loud, but more deep than anything, not a bad sound by any means. I am curious what this does to the engine in terms of backpressure (or lack thereof) or torque I guess you could say.

I'm sure this topic has been talked to death, but I figured I'd ask some of you who may have had experiences with this type of set up.

snoman · April 26, 2005

If so, what do you think? Specifically on the newer model 5.3L V8's? My brother has this set up (2.5in tubing out the back into 4in dia. x 18in long chrome tips) on his new Z-71 and it sounds awesome! Yes, it is loud, but more deep than anything, not a bad sound by any means. I am curious what this does to the engine in terms of backpressure (or lack thereof) or torque I guess you could say.

I'm sure this topic has been talked to death, but I figured I'd ask some of you who may have had experiences with this type of set up.

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With a closed loop engine, if you alter the exhaust tuning and back pressure too much you will see a loss of low speed torque and city MPG because of reduced efficency. Less is not always better when it comes to back pressure on modern engines as the are generally well tuning from intake to tail pipe at the factory to begin with and change the tuning to much and performance can suffer big time.

JCedar · April 26, 2005

On my 99' ext. cab GMC with the 5.3 I have a Y-pipe in place of the muffler. 2.5" pipe to 3.5" stainless tips. Sounds awesome. I love the sound of it, I didn't lose any performance, only gained. Fuel economy is not better but only because I love to keep my foot on the gas (Music to my ears). If I had to get exhaust again I would go straight back from the cats with 2.5" pipe with an H pipe or an x-pipe. I have two buddies one with an 01'ext cab. with a 5.3 with 2.5" duels right off the cats, no mufflers at all, no x or H pipe and I think he lost performance, sounds awesome though. The other buddy of mine has a 2000 chevy with the 4.8 and his is the same setup as mine just sounds a little quieter.

April 27, 2005

On my 99' ext. cab GMC with the 5.3 I have a Y-pipe in place of the muffler. 2.5" pipe to 3.5" stainless tips. Sounds awesome. I love the sound of it, I didn't lose any performance, only gained. Fuel economy is not better but only because I love to keep my foot on the gas (Music to my ears). If I had to get exhaust again I would go straight back from the cats with 2.5" pipe with an H pipe or an x-pipe. I have two buddies one with an 01'ext cab. with a 5.3 with 2.5" duels right off the cats, no mufflers at all, no x or H pipe and I think he lost performance, sounds awesome though. The other buddy of mine has a 2000 chevy with the 4.8 and his is the same setup as mine just sounds a little quieter.

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Have ya got any sound clips?

PeterbiltChrome · April 27, 2005

single cat, no muffler here... you can't beat the sound... i have it on a tbi 5.7 and it's 3" off the cat and y-piped to 2.25" for dual 3.5" tips. only crackles at high end and engine braking. nice and throaty...noise isn't too bad in the cab and i doubt i sense any loss in torque

smaller pipe = more crackle = more pressure

the stock manifolds and cats provide enough backpressure and the muffler isn't necessary

MS3DALE · April 27, 2005

I had the "no muffler" setup on my '93 and '94 K1500's (350-auto.) and loved the sound! I even got another 2-3 mpg. on the highway!

I wanted to go with this setup on my '97 and '99 K1500's but was scared what it would do to the backpressure with the OBDII system and that it would set off the check engine light,Guess I was wrong!

snoman · April 27, 2005

I had the "no muffler" setup on my '93 and '94 K1500's (350-auto.) and loved the sound! I even got another 2-3 mpg. on the highway!
I wanted to go with this setup on my '97 and '99 K1500's but was scared what it would do to the backpressure with the OBDII system and that it would set off the check engine light,Guess I was wrong!

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The TBI engine has different tuning than a Vortec engine and you cannot compare results between them. (the TBI engine is closer to a carbed engine in exhaust tuning than a Vortec is) With the noise on a Vortec you might think you are gaining but you are losing low end with low back pressure and the sound you like is from the reduced low RPM effiecency and the engine working harder to make up for it.

lerbud · April 27, 2005

I have had straight pipes on all my trucks!! It sounds great!! I had them on my 2000, 2002 & 2004 trucks all have not noticed any performance loss.

snoman · April 27, 2005

I have had straight pipes on all my trucks!! It sounds great!! I had them on my 2000, 2002 & 2004 trucks all have not noticed any performance loss.

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Because you are focused on the sound. If you dynoed the truck before and after, it would tell the tail clearly. To me the ultimate sleeper has a quite low restriction exhaust with gears a killer engine (maybe super charged) because it really rocks their boat badly when someone in a "bad" noisy truck gets toasted by a quiet one.

JCedar · April 27, 2005

Because you are focused on the sound. If you dynoed the truck before and after, it would tell the tail clearly.

I beg to differ, I changed mine to 2.5" pipe with a y pipe, as listed above. There was a very noticable difference in low end. NOT a LOSS. I noticed a gain in performance. It's not like I took out the cats and ran 3" pipes directly off the manifolds. I would bet money that I gained torque not lost it. I understand that these engines are touchy but not THAT touchy, with the mainfolds still in place and the 3" stock straight pipe to my 2.5" Y and tails afterwords is plenty of backpressure. That stock muffler sucks and weighs a ton, have you ever looked inside one of those things, might as well just stick a potato in your stock tailpipe!!

Just my opinion, if I'm wrong I'm wrong, but from seat of the pants feeling I noticed a gain not a loss!!

JML79 · April 27, 2005

JCedar,

So let me make sure I understand this:

the stock pipe size going into the muffler is 3in and you had a 2.5in y-pipe welded on in place of the factory muffler that goes out into 2.5in duals out the back? I think this is exactly what my brother did, but I am going to have to double check that. His chrome tips come straight out the back on either side of the spare and I am wondering if the sound in the cab will be affected by either bringing the tips out at an anlge in the rear corners or by leaving tips off and having the pipes dumped over the rear axle (out of sight for the most part)?

lerbud · April 27, 2005

I have mine run out the sides and it sounds great especially when someone annoys you while driving u can blast them with the pipes. lol

JCedar · April 27, 2005

Hey JML79,

You got it man, exactly what I have, I would imagine the sound in the cab would be a little bit louder going out the side corners but I'm not sure how much louder. I have always kind of liked the way that looked comming out the rear corners, plus when you go in tunnels and under viaducts you can really listen to your truck. I always give my truck gas so it will kick down when I go under viaducts or in tunnels.

It all depends too on if you snowmobile or anything like that. If I had to do my exhaust again, I would probably go out the rear corners because I back into snowbanks once and a while to unload/load my sled and the snow gets packed into the pipes. Just something to consider if you ever put yourself into that type of situation.

I forgot to mention, this is totally my personal prefrence but If I were you I wouldn't go with such long tips. That means you just have to crawl under there and clean em all the time. I do like the idea of big wide tips like the 4" ones but the really long tips just don't appeal to me. Just my opinion though.

Have a good one.

JML79 · April 28, 2005

Thanks for the info. I looked at my brother's truck last night and he has the exact same setup as you described on yours. I'm going to drive his truck for a day or two while he's in town and make sure I can handle the interior noise level-on the outside it sounds incredible though. I've ridden in his truck once, but I was in the backseat, which from my experiences with my past trucks, always has more of drone than the front anytime you change out the factory exhaust.

WhiteyZ71 · April 28, 2005

I test drove a couple of TBI's with a buddy the other day, hes lookin for his first real truck And I couldnt believe how good both sounded, no cats, no mufflers, just loud and kick ass sounding, you would have thought Ricky Rudd was driving past,a nd both were 5 speeds and they sounded really mean when engine braking....any tips on making my vortec sound like that? I have a flowmaster 50 on there now, sounds good, but way too quiet for my liking....I have a set of Bullets sitting in a box in my basement waiting to be installed, any advice on diameter for my tailpipes? I like the throaty sound more than the really deep headache on the highway tone....i'm thinking 2 or 2.25" after the bullets into some nice 3 or 4" tips....any suggestions?