Straights Or Mufflers?

BigP5792 · December 6, 2009

Right now I'm running a single glasspack w/cat on my 94 350 Sierra, but I decided to switch to duals.

The problem I'm having is deciding what kind of a setup to run. I've heard that running straight pipes with just the cat can mean loss of power due to decreased back pressure. Is this true? If so, is there a muffler I can get besides a glasspack that will give me the LOUD that I want? ( I also dont want to spend a fortune. I found a shop that will do just straights for $210)

And for all you people out there that are going to comment saying that loud exhaust is inconsiderate, save your breath and don't reply.

Nytemare · December 7, 2009

Right now I'm running a single glasspack w/cat on my 94 350 Sierra, but I decided to switch to duals.
The problem I'm having is deciding what kind of a setup to run. I've heard that running straight pipes with just the cat can mean loss of power due to decreased back pressure. Is this true? If so, is there a muffler I can get besides a glasspack that will give me the LOUD that I want? ( I also dont want to spend a fortune. I found a shop that will do just straights for $210)

And for all you people out there that are going to comment saying that loud exhaust is inconsiderate, save your breath and don't reply.

You have a Vortec engine...you will lose power with anything that's not stock. But we can minimize that impact.

If you want to go with duals...go with 2.5" pipes MAX and a reverse mounted glass pack...that's as loud as it gets. and the small pipe will allow you to retain a lot of power...Keep your cats though....

Or just pop out your existing glass pack and flip it around...it will be a whole lot louder, and you will have the same power you have now.

As far as loud exhaust being inconsiderate....most everyone here has a modified exhaust....and I say LOUD PIPES SAVE LIVES....just like the Harley guys say.

kylea · December 7, 2009

Get an IMCO Xtreme muffler. It will provide loudness and backpressure so you shouldnt loose too much power. It is a one chamber muffler. They also make the Pro witch has 2 or 3 chambers I cant remember.

desrtrat · December 7, 2009

you do not want any back pressure, what you want is a exhaust that still scavenges the exhaust out of the cylinders and keeps the exhaust speed up. if you want true duels straight pipes, you will need a H or X pipe in there or your low end TQ will go away...IMO.. straight pipes sound like Fido's a$$

BigP5792 · December 7, 2009

Thanks for the fast replies guys. You all gave some good advice. I've been doing some thinking and I want more of a performance sound than a straight pipe sound. I've been looking at mufflers like flowmaster, magnaflow, dynomax, and IMCO. Which muffler will give me the best tone and loudest sound? And I was also wondering If I decided to get mufflers , would the shop most likely just Y pipe it after the cat then to the mufflers? In other words Is there any way I can get more loud out of them as far as muffler placement?

Nytemare · December 7, 2009

you do not want any back pressure, what you want is a exhaust that still scavenges the exhaust out of the cylinders and keeps the exhaust speed up. if you want true duels straight pipes, you will need a H or X pipe in there or your low end TQ will go away...IMO.. straight pipes sound like Fido's a$$

This engine needs back pressure or he will have burnt valves. Low ("0")back pressure means the exhaust is unrestricted, and the engine will draw more air into the combustion chamber, more air and the inability of the OBD I system to properly modulate fuel delivery create a proper air fuel mix will result in a lean mixture and burnt exhaust valves. I know the O2 sensor does correct...but its not really good at it...its gets the mixture close...its made to work with the stock setup, anything changes, like larger exhaust, or cold air intake..etc, you should have the ECM reprogrammed. A 94 doesn't have this option, just a chip if he had a performance chip, than low or "0" back pressure would be fine, as the fuel mixture is bumped up as a chip is usually tuned for people with duals and CAI's.

Now with an OBD II system it does get better...but still not great without a way of adjusting the lamda of the air/fuel mixture. A wideband and tuning software is really the only way to do it for sure.

It was fine on old carbed vehicles...they always ran rich from the factory, or you could set them a little rich when you popped on a performance exhaust...but without tuning software you cant do shit to newer engines.

Nytemare · December 7, 2009

Thanks for the fast replies guys. You all gave some good advice. I've been doing some thinking and I want more of a performance sound than a straight pipe sound. I've been looking at mufflers like flowmaster, magnaflow, dynomax, and IMCO. Which muffler will give me the best tone and loudest sound? And I was also wondering If I decided to get mufflers , would the shop most likely just Y pipe it after the cat then to the mufflers? In other words Is there any way I can get more loud out of them as far as muffler placement?

If you want them loud...pop the muffler where it is now...or 2 if you go duals...and have 2, 90* turn downs right off the muffler, under the bed, pointing straight down at the ground.

As far as a nice tone...I love my Flowmaster Super 44, and its pretty loud when I'm on the gas. All the ones you mentioned are nice mufflers though.