The Exhaust Thread To End

Schmids5.3l · July 18, 2007

I found this on gmhightechperformance.com. He does a base line stock as a rock dyno, dyno after cat back exhaust installation, and dyno after header installation. Truck year isn't stated, but it's probably an 01+. The truck itself is a Silverado K1500 reg cab short bed. Engine is a LM7 (5.3).

http://www.gmhightechperformance.com/tech/...atback_install/

If you don't feel like clicking on the link, here's the dyno numbers: 244.1 rwhp and 276.3 lb-ft torque stock, 251.8 rwhp and 283.1 lb-ft torque (+ 7.7/6.8) with cat back system, and 261.6 rwhp and 293.4 lb-ft of torque (+ 9.8/10.3) with headers. So to break it down, cat back gave 8 rwhp and 7 rwtq, headers have 10 rwhp and 10 rwtq. As he states, an intake would benefit more and you would have better gains with tuning.

svensk · July 18, 2007

Finally a dyno chart to review backed up claims! It's really too bad he didn't have an air intake mod on there. That really would have been nice to finally see. According to the chart the cat-back system he used did not remove/redistribute the low end torque he did actually gain a few ponies down low. I wonder if you can achieve similar gains just by swapping out the stock muffler which is really the only restrictive spot in the whole stock system.

Schmids5.3l · July 18, 2007

I'm not sure, but I don't see why not. The only controversial thing I can think of about his tests was the cat back system, it's pretty much a straight through system, no chambered/baffled/ mufflers. So the stainless works cat back used, or a Borla, Magnaflow, SLP loud mouth, regular glass packs or straight pipes, or Corsa could be more beneficial than traditional mufflers since they don't have resonators and chambers and other stuff to restrict velocity. Just a thought I had. But it's still a pretty accurate test to prove cat backs do in fact increase power. Not much, but it's something on the side along with the sound you wanted for buying one in the first place. I'll take 8hp/7tq at the wheels any day for the cool sound I want with any V8 equipped vehicle I have.

I agree it would be cool to see the individual benefits of each mod to the other mod. Like dyno with intake alone. dyno with cat back alone. Dyno with both intake and cat back to see how much more you gain total with them benefiting each other.

I might search through that website and websites like it later, because I've seen another page like this one, might even be the same truck and website (I remember the truck looking very alike, it was 4wd too), but some guy adds sway bars, suspension goodies, wheels and tires, and hits the slalom, I think he compared stock to modified like this one did too.

MikeRS1981 · July 18, 2007

See I have an 07 NBS, and I just opted for the flowmaster muffler. I was told not to bother with a cat back because the pipes are brand new, and are already 3", so theres no point in buying different exhaust piping. I didnt really drive the truck that much without the exhaust, I got it put on the same week I bought it. But, it does feel quick if that helps out at all.

04silverado1500 · July 19, 2007

i wonder what my exhaust would gain me. i have it cut off before the muffler and a y pipe right after that splitting it into two seperate 2 1/4 in. pipes all the way back to my 18 in. long by 3 1/2 in. tips. alot of people tell me i have lost power but i think the pipe is small enough (for a reason) to keep enough back pressure.

omegafiler · July 19, 2007

Yet you will still continue to hear people saying that CAI/Exhaust mods do nothing but make more noise.

It's good to see a real dyno prove what my butt dyno tells me everytime I accelerate though.

Heck, I had even done a few dyno comparisons on my old grand prix GTP with various mods including pcm, exhaust, CAI, pulley, etc. The best gains were when everything was working together - that's how ya get the power!

Sly · July 19, 2007

Yet you will still continue to hear people saying that CAI/Exhaust mods do nothing but make more noise.

It's good to see a real dyno prove what my butt dyno tells me everytime I accelerate though.

Heck, I had even done a few dyno comparisons on my old grand prix GTP with various mods including pcm, exhaust, CAI, pulley, etc. The best gains were when everything was working together - that's how ya get the power!

I would like to see a dyno sheet with a set of shorties, to see if they are even worth the money.

Schmids5.3l · July 19, 2007

i wonder what my exhaust would gain me.

Probably the same as previously stated. The cat back they tested is close to straight pipes.

Nytemare · July 20, 2007

Only problem I see is that the dyno starts at 3600 rpm...theres nothing to show if you lose power in the low end.

But none the less...good find man.

TxTruckMan · August 31, 2007

I've had the Corsa on my 5.3L 2003 Yukon for a little over 2 years now and I can tell you that you will loose a little on the low end. Once the novelty of the awesome sound wore off (several months), I was able to get some real tests of my MPG. I lost about 1 MPG in town and 1.5 or 2 on the highway. Only other mod is a K&N filter. I've since added 22" rims and have lost even more mileage, but my Yukon looks and sounds cool! Next mod will be a tune (probably Superchips) to recalibrate my speedo and recoop some of my lost low end power.

svensk · September 1, 2007

I've had the Corsa on my 5.3L 2003 Yukon for a little over 2 years now and I can tell you that you will loose a little on the low end. Once the novelty of the awesome sound wore off (several months), I was able to get some real tests of my MPG. I lost about 1 MPG in town and 1.5 or 2 on the highway. Only other mod is a K&N filter. I've since added 22" rims and have lost even more mileage, but my Yukon looks and sounds cool! Next mod will be a tune (probably Superchips) to recalibrate my speedo and recoop some of my lost low end power.

I think if you have a PCM tune to go with the exhaust upgrade you won't lose that low-end. In fact you might gain on the low end with the combo of intake+exhaust+tune.

Wingnut · September 2, 2007

Only problem I see is that the dyno starts at 3600 rpm...theres nothing to show if you lose power in the low end.

But none the less...good find man.

That's what I noticed too.

cmoore74 · September 6, 2007

I've had the Corsa on my 5.3L 2003 Yukon for a little over 2 years now and I can tell you that you will loose a little on the low end. Once the novelty of the awesome sound wore off (several months), I was able to get some real tests of my MPG. I lost about 1 MPG in town and 1.5 or 2 on the highway. Only other mod is a K&N filter. I've since added 22" rims and have lost even more mileage, but my Yukon looks and sounds cool! Next mod will be a tune (probably Superchips) to recalibrate my speedo and recoop some of my lost low end power.

My buddy put a Corsa exhaust on his avalanche and swears he gained about 1/2-1 MPG with no loss of low end. His is the single side exit. I've been debating one for a while, but don't want it if I'll loose low end or mileage.

Is yours the single side exit or duals?

If single side exit, after a ton of research (I swear I have OCD when it comes to researching turck parts before I buy), yours is I think the first post that states they lost performance and MPG when switching to a Corsa cat-back if single side exit.

I have heard a few comments about loosing low end with the dual exhaust, but 1-2 MPG is quite a large loss.

Schmids5.3l · September 8, 2007

Here's the suspension article I was talking about eariler, same truck same guy. The truck is an 04. He also gets HP Tuners and takes out abuse mode, 50% of TM, rasies all shift points to 5900 rpm ect. I want the wheels he uses too, I'm looking for them..

http://www.gmhightechperformance.com/tech/..._modified_truck