2014 6.2 exhuast power loss

[Bvonscott]

I just bought a 2014 sierra All Terrain 4wd with the new 6.2 a few weeks ago.

I wanted to upgrade the exhaust first since the stock one was too quiet, so I went to my local exhaust shop that has a mandrel bender and had them put a flowmaster from the muffler back on. My last truck had a 3" cat back with a dual chamber 40 series single out the back, it sounded good and increased the power. This time I wanted it louder so they did a super 44, which has a single 3" in and out. We measured and The stock exhaust uses 3.5" piping, but necks down to 3" at the stock mufflers in and out, so this would be a simple swap. But since this shop does not do 3.5" mandrel bends, we put a 4" mandel bent piping from the muffler back and a single exit straight out under the bumper.

 

Anyways I love the sound its louder and deeper than my old one, but there is noticeable loss in torque when accelerating. It still gets on it but not quite as fast as stock. Does anyone know where I messed up? Would adding a intake system be the answer? Or is this exhaust change either not providing the necessary backpressure or do I need a different brand? I only spent $300 and don't want some crazy $1000 setup just to get it louder and add more torque and mpg.

[Danthaman69]

Its 4" from the cat through the muffler all the way back? Is that what they did?

[Bvonscott]

No just after the muffler. Its all stock before the muffler. Which is 3.5"

[MikeNH]

Mufflers and exhaust systems on modern vehicles rarely actually offer a usable increase in power, it's all audio horsepower. Things like exhaust and intakes tend to cost low end but gain at the top end of the RPM range. Never been impressed with flow master though, had a kit on my 2003 and it rotted like crazy but chances are that's a non-issue living in California.

[Danthaman69]

Not enough back pressure. Anytime you change pipe size it also changes your horsepower and torque range. 4" is too big. 6.2l really only need 2.5-3" exhaust. There is not enough horsepower and torque until you get over 800hp power range. For that size exhaust. Your losing your power over 3" exhaust

[kstruckcountry]

I wouldn't think 4" would be enough to slow the exhaust flow down enough to hurt, but I guess it did lol. Also your factory muffler flows better than a flowmaster.

[Bvonscott]

Danthaman the stock exhaust uses a 3.5" pipe all the way.

Anyways thanks for the replies, i agree on the backpressure not to mention I looked at the stock muffler which I kept, it is a straight through. So, knowing this, my first change is to replace the muffler with one that has a straight through. So.. Magnaflow? Corsa?

 

After that, if there is no change, then I will also find a way to get 3.5" tubing out back as well.

[Danthaman69]

Corsa, Magna flow, borla would be good choice. I'm using magnaflow on mine. Putting that on Monday. I'm goin to 3" exhaust. I'm getting a muffler shop to do mine.

[Danthaman69]

I wouldn't think 4" would be enough to slow the exhaust flow down enough to hurt, but I guess it did lol. Also your factory muffler flows better than a flowmaster.

It actually does slow it down from not enough back pressure. When I drag raced I did tons of research on exhaust on how it effects your HP and tq.

[Powermedic]

What do you guys suggest for the 2014 sierra 6.2L? Borla / Flow / Magma techincally do not have anything out yet for that year.

[SILVERADOSC540]

Last time I suggested a relationship to proper backpressure on here I got my wrist slapped by someone who knew more than me. Back pressure makes a difference, and you have to tune accordingly. Thanks for taking the "pressure" off of me Daniel.

[MikeNH]

What do you guys suggest for the 2014 sierra 6.2L? Borla / Flow / Magma techincally do not have anything out yet for that year.

 

Find the brand muffler you like and have it welded in. Only choice for now.

[Danthaman69]

I have dealt with enough exhaust questions to know what people need to know. So I don't mind. Not everyone wants to hear the truth though.

Op you can try to talk magna flow, borla, corsa or whoever you like in exhaust to see if they are looking vehicles to test fit. They will usually need your truck for 2 weeks.

I really like magna flow products. Just my opinion.

Go with exhaust you like. 6.2l sound great with exhaust.

I have always done customs exhaust systems with my trucks and cars. Its cheaper and its exactly what I want.

Doing yourself is so much more pride you have.

Find reputable muffler shop you know and ask them. Usually they have any muffler but if not order one have them do it you don't wanna weld it.

Some people like slip on exhaust. Hope this helps you out

[Jon A]

If you aren't measuring on a dyno, you don't really know what's going on. The "butt dyno" is very inaccurate, especially when other factors are involved such as changing the sound. Much like smell changes the taste of food--it really doesn't but you think it does--changing the sound of the engine can make it "feel" stronger or weaker. With the more open exhaust you may hear it straining/lugging at low RPM more than you did before giving you the impression that it's lugging more than before even if it really isn't.

 

I agree if the stock system is 3.5" thoughout with a straight through muffler, there probably isn't much to gain--certainly not much to loose either. I wouldn't expect a catback to make more than a few lb-ft difference at low RPM either way, much too small a change to accurately observe with the "butt dyno."

 

I suggest choosing a catback based on the sound you want, the looks of the pipes/tips, etc. That's enough to make it a worthwhile mod certainly--as well as getting rid of the flapper valve which is so problematic. For noticable power gains (especially at low RPM), start thinking headers, tune, etc.

[KARNUT]

The rule of the game is back pressure helps low end to a point, less back pressure or noise helps HP high end RPM to a point. Its there you just moved it, which is good with the HP you have, a tuner will enhance it all.