I've been reading through all of the threads pertaining to performance exhaust. Most of us in this forum base many of our answers off of personal opinion vs cold hard facts which is what makes this site great but after days of searching I'm totally stumped on what to do with my exhaust. Most agree Flowmaster is geared for sound where as Magnaflow is geared toward performance and sound. I had a few extra bucks to spend so I started with a Flowmaster muffler swap ($110). I kept the resonator on and stuck with my stock pipes. It's sounds pretty damn good (though a bit pickup-ish) but is still really loud. Am I feeling more off the line? Is it faster when I kick it in on the highway? I frankly can't tell. It sounds so much more aggressive that it's easy to think it's actually performing better but it could all be in my head.

Here are my questions..............

What's the best for performance, Flowmaster or Magnaflow? What does a full cat-back system buy you vs a simple muffler upgrade? I'm ready to pay for the best but I want to back it with numbers.

Thx

 

a full cat-back system replaces all the exhaust from your cat, back 2 your tailpipe ( just in case that wasn't totally clear in the name). these systems have smoother, more fluid bends, better flow throughout the system 2 help relieve the back pressure. add a header kit to flow better than your factory cast jobs with a y-pipe, & u'll see even better performance that won't just b in your ears. as 4 who's system is better, i'm not sure. i've never tried Magnaflow, but am quite happy with my Flowmaster set up.

 

70mopar,

Excellent reply, thank you. I agree with everything you said. I guess the real thing I'm trying to understand is the real benefit for the price you pay for a cat back system. For instance, let's say we're told a cat back system will give you 15 more horse power. How much of that can you tie to "smoother, more fluid bends, better flow throughout the system"? I'd assume 95% of the performance difference would be in the muffler and the last 5% could be improved by the pipes. Is that some what accurate? If that's the case than a $110 muffler upgrade makes much more sense than a $500 cat back upgrade.

Great point about the headers. I hadn't even thought of that. This may be worth a separate post but do you know of a header set for the '07 Tahoe that would be worth the money? Can you give an guesstimate on the horse power gain of a good header?

 

i'd say your % spread might be off, just a touch. i'd say a better flowing cat and pipes would help out the flow, better than just adding a freer flowing muffler. sure it's some $, but if u want it, u gotta pay for it. i know.... u just want 2 spend it right, the first time around. as for what power a header will yield all depends on the design off it. equal length headers generally get higher #'s, but limited space is always an issue. ceramic coating on the headers will also yield better gains, longer life and lower under hood temp.

 

I had a magna flow installed that was single input, dual out. It basically went: cat>magnaflow>two pipes out. It was LOUD as hell and the drone drove me nuts... I went back and had a resonator put on. It was good for a while, but the drone took over again, especially around 2000 rpm's / 70 mph. I had enough and ripped it off. I then had a Flowmaster 70 series installed and love it. Very quiet in the cab, but aggressive sounding outside. Performance seems to be about the same...

 

marsalisjr,

Which series and size flowmaster do you have? This will make a huge difference on sound? If you have the 40 series, it is loud and probably will have more of a truck sound. From my personal experience with about 25 different muffler and exhaust set up's I was most happy with the magnaflow muffler sound.

As for performance, it is my opinion that you arent going to get much, if any performance gains from an exhaust system. Newer vehicles have pretty free flowing exhausts. If you get headers, remove, cats, and new exhaust system you would notice a difference. But simply changing the exhuast for an aftermarket system probably wouldnt create much gain. IMO it is the volume/sound of the exhaust that makes you think/feel it is faster. I personally have never noticed gains from just the installing an aftermarket exhaust system.

The aftermarket exhaust systems use what is called Mandrel bends! They dont break down the pipe at the bends, they keep the same diameter thoughout the bends. Therefore, they say you get a more free flowing exhaust.

If i were to put exhuast of any kind on my 2007 tahoe I would put on a Magnaflow muffler. I would buy the muffler from www.performancepeddler.com, i would take the muffler to my shop have them rip off the factory exhaust and put on a new tailpipe and tip. You could just have them cutout the muffler and resonator and put on the magnaflow, that is up to you. Again, this is my preference, I am not telling anyone what to do or what is actual facts! Just my personal experiences.

You can go to magnaflows website and listen to some 2007 chevy 5.3 vehicles to get an idea of what the magnaflow will sound like with our 07 tahoes.

 

Thanks to all for your advice.

Biglg, you're correct. They stuck a Flowmaster 40 on my Tahoe and it's definitely loud, even with the resonator but it's not horrible. What Magnaflow muffler would you go with? If I go to a single in dual out muffler and remove the resonator will it make it extremely load? I want to keep it reasonable. How much difference does the resonator actually make?

 

The resonator will make a differnce. But i can not tell you how much as i have not heard one with it on vs. off! If I personally were putting exhaust on the Tahoe, I would not put a resonator on. However, i will not be putting exhaust on the tahoe, the wife drives it to frequently and hates it loud!

I have researched exhaust sytems for a long time. Everyone talks about cab drone, cab noise, etc. I personally have never found any exhuast that is loud ouside that doesnt cause drone and cab noise. The two come hand and hand. Are there some that are worse than others, yes! But if you want it to sound good ouside, it is going to hurt a little on the inside!

As for the muffler, i would contact magnaflow and ask them what the model number of the muffler is that is included in their kit! Get that part number then find the muffler! If it is only a si/so, which I think it is just take the measurements of the muffler casing and find the same thing but only si/do if that is what you want. You know that the muffler they have determined to use is after significant research and probably best for our vehicles. I have always just purchased the muffler included in the kit and taken it to my local shop who is very good and had them install it on their pipes!

If you get the muffler number from magnaflow I would love to know just the muffler number, not the entire magnaflow replacement exhaust kit number. Just the muffler part number included in their kits for the 2007 tahoe. Let us know if you get it!

 

When manufacturers quote hp gains when using their product, always find out the rpm range that the increase occurs in. The ones I've checked are usually in the upper ranges where we do very little driving, at least in a family car or SUV. I personally would prefer something that produced more low end torque because that's what gets you away from the stop lite. Horsepower is what gives you your top end. Good luck on your muffler search and let's us know what you get and results.

 

this isn't really an apples-->apples comparison.... but here i go.

2wd '04 Tahoe with the 5.3 and 3.24 gears.
With 10,000 miles on the odo, I installed a K&N FIPK. The next day, I had a Flowmaster installed. I had asked for a 3 chamber, but the idiot installed a 40 series. I was charged right, so i didn't worry about it.

Here's the deal. I inspected the exhaust on mine. It is already like 2.75" diameter and the bends are VERY smooth and appeared to be comparable to mandrel bent pipes. All I did was have the guy cut out the OEM sandbag and weld the Flowmaster in. The sound... oooohhh, the sound. I love the growl. Wanna hear it?SOUND CLIP

Yes, there is an overbearing drone at 2100 RPM, which just happens to be the "sweet spot" for normal accelleration, and cruising at interstate speeds.... or towing with the O/D off.... But I think I can admit to seeing improvements.

At the time the mods were done, we were commuting from Ray City, GA to Jacksonville, FL 2-3 times a week. The trip litterally took 1 tank of gas. Left the house full, came back on "E". The first day we went after the mods, we had just under 1/4 tank. This repeated for the remainder of our trips to JAX. Yes, it was early on in the life of the vehicle which typically sees poor fuel mileage, but it was like flipping a switch.

Remember, that an engine is nothing more than an air pump. To see real gains, you have to improve efficiency at BOTH ends.

Also, the '07 having a resonator.... the '04 doesnt have one. Removing it will make it louder, I'm certain. I love the growl, but I hate that droning at highway speeds.

I tried to knock down the droning... and found a SLIGHT decrease in noise.... Check link below if interested.
www.geocities.com/b1pig/tahoe.html