Exhaust Opinions

[89Suburban]

Well, sounds like my stock muffler finally blew open. I'll be climbing under there this weekend to check it out and will take some pics. Any suggestions on a street legal exhaust mod? I'll be using the original Y-pipe and cat. I haven;t really seen much in the way of a cat back system for this truck. I'll might even just use the existing stock pipes and just change the muffler. I would like the exhaust to exit out the back. It comes out the rear drivers side right now and is a pain in the ass when parked the exhaust blows right towards the drivers windows and ****. Just wanted to hear some opinions on what you guuys think or have tried. I am not sure if I want it to rumble or keep stock quiet. Thanks.

1989 GMC V-1500 350ci Auto 4x4

 

[skysurfer]

I did a 3" cat-back with a single-in single-out Dynomax muffler. It has a nice rumble when you stomp on it but doesn't drone on the highway and is dead quiet at idle.

I was going to get a Flowmaster because that's what everyone has. Many thanks to the muffler guy that talked me out of it, there's a big difference between a truck cab that's well ahead of the noise and a Suburban where your passengers are right above it.

No need to get fancy with dual outlets unless you really want them, a single 3" pipe will easily flow the exhaust from your stock LO5.

 

[Old77]

You won't find an out of the box cat back exhaust system so you will most likely need a muffler shop to run exhaust for you if you're changing it at all unless you can weld.

With that said, you'll get a ton of differing opinions from people on this. If I was you I'd search YouTube and listen to different mufflers and see what you like the best. I've got true duals on mine with no cats. The mufflers are 40 series flowmasters and I love the sound of them!!! If you wanted a little quieter you'd go with a 50 series and then the quietest would be a 70 series. The other brands offer similar grades as well.

So it all pretty much depends on what sound you want and what loudness you'd like for it to be at. YouTube is your friend for this

 

[89Suburban]

If you don't know me by now, I'll be doing this el cheapo way. Plus I have a connection at the parts store where I can use my "fringe benefit" package. I'll most likely be taking off the existing u-bolt muffler clamps and replacing them with stainless steel band clamps. Just need a muffler decision really I guess. And I will be doing something with the tail pipe to exit out the back or at least point down or something, the fumes on the driver side thing has really been a thorn in my side.

I'm not really interested in putting duals on. I like that post about the dynamax muffler. I had a 40 series Flowmaster on that white '89 K-1500 in my photo album. That has a nice rumble and I had duals exiting out of the FM out the side in front of the rear tire on the pass side. You can barely see the tips in the photos.

Has anybody ever run just a straight pipe with just the cat? Is that legal?

 

[89Suburban]

I did a 3" cat-back with a single-in single-out Dynomax muffler. It has a nice rumble when you stomp on it but doesn't drone on the highway and is dead quiet at idle.

I was going to get a Flowmaster because that's what everyone has. Many thanks to the muffler guy that talked me out of it, there's a big difference between a truck cab that's well ahead of the noise and a Suburban where your passengers are right above it.

No need to get fancy with dual outlets unless you really want them, a single 3" pipe will easily flow the exhaust from your stock LO5.

I'm still learning the acronyms here, LO5?

I like this idea so far. I'll have to check out youtube this weekend.

 

[skysurfer]

LO5 is just the designation GM gave your 5.7 engine.

 

[89Suburban]

LO5 is just the designation GM gave your 5.7 engine.

Thanks dawg.

 

[skysurfer]

I will be doing something with the tail pipe to exit out the back or at least point down or something, the fumes on the driver side thing has really been a thorn in my side.

A turn down exhaust will still draw fumes from the rear doors, the tip needs to be all the way out the back or near the rear wheels where there's turbulence to take the exhaust away.

 

[89Suburban]

A turn down exhaust will still draw fumes from the rear doors, the tip needs to be all the way out the back or just ahead of the rear wheels where there's turbulence to take the exhaust away.

On another truck I had before I bought one of those tractor flappers and stuck it on the pipe and it pushed fumes towards the ground at a stop but opened up cruising. I may be doing that too. I hear what you are saying about the rear doors. I'll have to keep the discharge where it is.

 

[89Suburban]

@Skysurfer

Which Dynomax did you get, seems there are a few different ones.

http://www.dynomax.com/mufflers.php

 

[skysurfer]

I went and looked at the muffler itself but there's nothing stamped on it. I'll see if I can dig up the original receipt.

Edit: Found the warranty card, it's this one.

http://www.jegs.com/i/Dynomax/289/17769/10002/-1

 

[Old77]

Has anybody ever run just a straight pipe with just the cat? Is that legal?

This all depends on your local noise ordinance more than anything I think....

 

[Manbearpig]

Man I had a 3" bullet on my K5 and it was louder than hell. Set off car alarms everywhere I went

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Pretty happy with the Hooker Aerochamber I have on it now
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[skysurfer]

...and if that's the original cat it would be pretty loud. At 150k miles I was having trouble passing the smog tests. Found out the cat was just a burned out shell, new high-flow cat and it sails through the sniffer no problem.

 

[89Suburban]

I went and looked at the muffler itself but there's nothing stamped on it. I'll see if I can dig up the original receipt.

Edit: Found the warranty card, it's this one.

http://www.jegs.com/i/Dynomax/289/17769/10002/-1

Sweet. So it's 3" in & out, and is the a center inlet and off-set outlet then?

Did it match the original pipes ok? Length wise it was good?