Exhaust for Performance??

[dlcooldude]

I've got a 1999 Suburban w/ 5.7 and am looking to replace entire exhaust system (from stock manifolds back). Have seen replacement 'performance' exhaust systems from Magnaflow(?) which basically replace the stock system. Some have dual inlet/single outlet and others single inlet/single outlet mufflers. Anybody have experiences - plus or minus - with these systems - do they achieve performance gains, mileage gains, etc. Are there any good true dual exhaust systems out there you'd recommend? Any recommendations on headers if I wanted to?
Thanks

[MT-2500]

Originally Posted by dlcooldude

I've got a 1999 Suburban w/ 5.7 and am looking to replace entire exhaust system (from stock manifolds back). Have seen replacement 'performance' exhaust systems from Magnaflow(?) which basically replace the stock system. Some have dual inlet/single outlet and others single inlet/single outlet mufflers. Anybody have experiences - plus or minus - with these systems - do they achieve performance gains, mileage gains, etc. Are there any good true dual exhaust systems out there you'd recommend? Any recommendations on headers if I wanted to?
Thanks

Headers on a daily driver are a big pain.:sarcasm1:

Sometimes you may lose power and gas mileage.

The only place for performance exhaust is on a off road engine and truck engine built and setup for off road perfoirmance.

[j cAT]

Originally Posted by dlcooldude

I've got a 1999 Suburban w/ 5.7 and am looking to replace entire exhaust system (from stock manifolds back). Have seen replacement 'performance' exhaust systems from Magnaflow(?) which basically replace the stock system. Some have dual inlet/single outlet and others single inlet/single outlet mufflers. Anybody have experiences - plus or minus - with these systems - do they achieve performance gains, mileage gains, etc. Are there any good true dual exhaust systems out there you'd recommend? Any recommendations on headers if I wanted to?
Thanks

with these vehicles the OEM stock exhaust with the 5.7L engine is a very good system..using larger pipes and or full duals exahust with headers will gain only , if you plan on towing or hauling large heavy loads...

many ford owners do this muffler mod because ford has exhaust systems that are resticted and many that I know with these have found good results...

my vehicle has the original exhaust its 10yrs old OEM, with still no issues in the rust belt...when it does go I plan on getting a fully s/steel exhaust of the same pipe diameter and some low restriction muffler...


you will not gain any MPG with these exhaust changes ...or get any more power ...

[Elbert]

any real gains in performance for stock engine...by chaingin exhasut...no

Would I put headers on a stock engine of any sort..no (royal pain in the but for very small gain in performance).

I would entertain swapping over to a Magnaflow muffler that is made to replace your stock unit...only if you like a more performance orientated sound. Don't do anything related to the exhaust on a stock vehicle with the expectation that you will benefit either in power or fuel milage much at all.

I only do it beacuse I like the sound, or the muffler or pipes need replacement.

[Blt2Lst]

I really don't see how a less restrictive exhaust system can be anything but beneficial to almost any engine in any vehicle.
A free flowing exhaust improves efficiency which in turn improves performance and fuel economy in most cases.
Actual gains will vary based on how restrictive the system is to begin with.

I am not saying that a toyota corolla should have 3" pipes from the headers back but there is a optimal pipe size for optimal performance and bigger is not necessarily better.

Many exhaust systems from the factory are restrictive due to design and manufacturing criteria, ie: space limitations in the engine compartment, poorly bent tubing with kinks instead of smooth mandrel bends, sound requirements and cost.

I would never hesitate to have a free flowing exhaust system including headers installed on any of my V8 equipped American cars

Just my

[Elbert]

the question is how much have you increased your performance by adding headers, mufflers...etc to a stock engine? The real answer is not by much at all. I hate stock exhaust setups on most cars and its one of the things I generally change.

Headers are hands down a waste of time on a stock engine... Yes you will have very small incremental gains in fuel milage and power....but generally speaking its not worth the money or effort.

Now if you want to do it for the sound...with the expectation that you'll get that much benefit...then just understand what you are really doing.

Headers generally don't last that long, and are prone to exshust leaks, they also increase the underhood temps a great deal and will melt any wires in the near vicinity.

Now if talk about swapping cylinder heads, intake manifolds, camshafts, and along with that headers, dual exshuast etc....then you are approcahing as a "team effort" and you'll see some benefit. Generally there are lmits on what you can do to a stock engine will all the fuel and emission controls, unless you want to get into the world of PCM/ECM programming and then you've stepped into the next level.

#1... you can't get crazy with the exhaust on a 99 vortec..as it has 4 O2 sensors that have to be there plus converters. Yea you could put o2 compliant headers and a performance muffler on the truck but in reality not much gained.

IF me..as I said above... Go by local muffler shop and get a good magnaflow replacement muffler to swap out for the stock one, leave OEM exhaust manifolds on the truck and call it a day.

I like a good sounding American V-8 like anyone else...but I'm just saying that in reality...the actual HP or fuel milage gains are very minimal with changes to the exhaust and what ou can legally do (depending on where you live).

[j cAT]

Originally Posted by Blt2Lst

I really don't see how a less restrictive exhaust system can be anything but beneficial to almost any engine in any vehicle.
A free flowing exhaust improves efficiency which in turn improves performance and fuel economy in most cases.
Actual gains will vary based on how restrictive the system is to begin with.

I am not saying that a toyota corolla should have 3" pipes from the headers back but there is a optimal pipe size for optimal performance and bigger is not necessarily better.

Many exhaust systems from the factory are restrictive due to design and manufacturing criteria, ie: space limitations in the engine compartment, poorly bent tubing with kinks instead of smooth mandrel bends, sound requirements and cost.

I would never hesitate to have a free flowing exhaust system including headers installed on any of my V8 equipped American cars

Just my

the fact is on these vehicles the exhaust is where GM did the right design and did not cut corners like the ford trucks..this is the major item that is , what I found , to be very good in performance ..then on these forums I found many complaining " why did I lose power / MPG after installing my extremely large no restriction exhaust ? "

the pcm is programmed to operate componets like the EGR valve , with lower exhaust pressures this then screws up the engine controls ..

on my 96 impala with some of these very low restrictive exhausts you have to change the EGR to, the firebird engines EGR, to get the proper operation for the engine ...

like you say many vehicles made did not have the correct sized exhaust ...this was many years ago...GM worked this engine for max performance to be ahead of the number's competition...with the other manufacturers..

[consultIII]

Originally Posted by Blt2Lst

I really don't see how a less restrictive exhaust system can be anything but beneficial to almost any engine in any vehicle.
A free flowing exhaust improves efficiency which in turn improves performance and fuel economy in most cases.
Actual gains will vary based on how restrictive the system is to begin with.

I am not saying that a toyota corolla should have 3" pipes from the headers back but there is a optimal pipe size for optimal performance and bigger is not necessarily better.

Many exhaust systems from the factory are restrictive due to design and manufacturing criteria, ie: space limitations in the engine compartment, poorly bent tubing with kinks instead of smooth mandrel bends, sound requirements and cost.

I would never hesitate to have a free flowing exhaust system including headers installed on any of my V8 equipped American cars

Just my

having some backpressure can increase scavaging effects; causing the exhuast to pull the intake charge into the combustion chamber more efficiently.

Did an exhaust change on my old fiero from exhaust manifold back...went too big on the pipe diameter and had no power out of the hole...was fine at high rpm and high speed. At least it sounded fast.

[iroc343]

I have a 2005 2500HD 6.0 and I have installed stainless steel headers and Flowmaster cat-back exhaust. While the truck sounds better, I can't say I've noticed much gain in either mileage or performance. If you decide to install an aftermarket exhaust system, and you drive the vehicle year round in the rust belt, bite the bullet and buy stainless steel. I got 2-3 years out of the aluminized steel system before it rotted out.

[Blt2Lst]

Originally Posted by Elbert

I like a good sounding American V-8

That's what I'm talking about..