Gibson or Magnaflow exhaust

Axxlrod · July 15, 2003

I want to add a cat-back exhaust system to my 03 Yukon 5.3, but I don't want a real loud sound. I want to hear more rumble when I'm on the gas, but not when cruising on the highway. From what I hear, Gibson and Magnaflow are quieter than most other exhausts.

I put new 20" wheels and tires on last week, and they definitely robbed me of some power. I need an exhaust that will not make me lose any low end. In fact, I need to gain power in the low rpm's, not the high rpm's.

I think I'll probably stay with the single in/single out design.

Which exhaust would you guys recommend?

Thanks.

MarkD · July 15, 2003

I would just replace the muffler with a Magnaflow.

awdvkd · July 15, 2003

I have Magnaflow two in two out w/ duals. It great at idle and crusing but throaty under gas. Almost no loss in low end torque, I lost more putting GY MTR's on than the muffler.

ShortCrew · July 15, 2003

I just did a Magnaflow on my truck. The sounds is very deep and mellow. You can barely hear it at all crusing on the freeway. It makes a nice deep rumble when you gas it. I highly recommend it.

Greg · July 15, 2003

I chose Gibson because it isn't supposed to cause any low-end torque, and I didn't detect any loss SOTP. It's not the most authoritative exhaust note, but at least my Av doesn't sound like a minivan anymore.

ricks · July 15, 2003

I put a Gibson dual sport ss/catback exhaust system on my truck. It gave my truck a much more aggressive sound without being annoying.

Axxlrod · July 15, 2003

I thought the purpose of adding an aftermarket exhaust was mainly for increased performance (power), and (secondarily) more throaty sound.

It sounds like adding an exhaust usually causes some low-end power loss. If that's the case, I won't do it. Why would anybody trade power and performance for sound?

For me, the purpose of adding the exhaust is to recover the low-end power that I lost due to the bigger (heavier) wheels and tires.

So the question is: Do aftermarket exhaust systems increae or decrease power?

Let's hear from the experienced.

petemata · July 15, 2003

I just did a Magnaflow on my truck. The sounds is very deep and mellow. You can barely hear it at all crusing on the freeway. It makes a nice deep rumble when you gas it. I highly recommend it.

I totally agree with Axxlrod.

Victory Red · July 16, 2003

I put new 20" wheels and tires on last week, and they definitely robbed me of some power.

I think I'll probably stay with the single in/single out design.

With the larger wheels, you might need to have the dealer reprogram your computer. I would think that any change in the outside diameter of the stock tires would require an adjustment to the computer. Could explain the sudden power loss with the new rims.

You've got to go with at least the dual outs if you want any kind of "rumble". I bought the SS Gibson Dual Sports and have been very happy with them. Just enough sound to let you know the engine is running at an idle, and loud enough to make you smile when you get on it.

Axxlrod · July 16, 2003

VictoryRed, I was very careful when I selected the new tire/wheel combination. The wheels are 20 x 8.5, so I went with a 285/50/20 tire. That size is within 1% of the original stock tire size. The overall tire diameter of the 20" wheel/tire is practically identical to the stock size.

So, to the engine computer there is no change.

The new wheel/tire combo is much heavier than stock. There is around 20 additional pounds of rotational mass at each corner now.

The engine has to work that much harder to turn these heavier wheels. That is the power loss I am trying to recoup.

awdvkd · July 16, 2003

Sounds like you need to visit westers garage site, that will get you back to original power plus! Hum.

chevy2000 · July 16, 2003

I just put a Magnaflow system on my truck and I love it. Nice sound when accelerating, but nice and quiet on the road when cruising. I would check into just replacing the muffler, unless you want dual exits. I got my stuff from www.bigexhaust.com they had pretty good prices for Magnaflow stuff.

Thanks

bigtruck21 · July 17, 2003

Definately go with a single 3 inch for more low end torque and dual 2.5 for more top end hp at a cost of some lowend tq (but how much who knows). The duals flow more and have less backpressure. Both magnaflow and gibson told me this. I am in the same boat you are Axxlrod. I want specific dyno numbers at all rpm ranges to find which best suits my style of driving. sporttruck tested the magnaflow single 3in on a 5.3L 03 and it gave like 12hp and 11tq peak with averages of 9hp and 9tq but only posted the rpms from 3700-5700rpm. I wish it would have the lower rpms listed too. I'm working on getting answers from both magnaflow and gibson. I know they have the dyno charts. I want performance first and sound second.

Tolliverme · July 17, 2003

I have a Gibson Dual Extreme Cat Back System. It added low end torque without getting to loud.

It is solid Stainless steel and took 2 hours to install.

The instructions tell you to cut the old pipe behind the muffler to remove the factory system but if you Jack the vehicle up and put the front leaf spring mounts on jack stands you can take the factory muffler and pipe off without cutting anything.

2001 1500 2WD 5.3 LT

jaslo · July 18, 2003

bigtruck21, let me know what you find out from magnaflow and gibson. I am like you, dont want to lose the low end torque. I do have the k & N fipk and have noticed no decrease in low end power or gas mileage. plus it seems the truck has a easier time keeping speed. I still have the stock muffler.