VCCA Home Forums GENERAL DISCUSSION General Discussions Tail/exhaust pipe sizes?

I have never been educated on the why and wherefores of tail pipe and exhaust pipes sizes and how it affects the performance of a vehicle.

I have owned my 2003 Chevy truck (6.0) over a year now and I think it is time to get that Chevy V8 sound out of the truck instead of the silence of the factory system.

What size pipes would be best for performance and mileage? I have used Flowmasters on other cars and I like them, but what cat. converter should I use?

Putting duel exhaust would be how much trouble? Best way is what?

Gator, I have considered duals on my trucks 2 350s and a 5300, The catalytic convertor presents a problem since the EPA standard was set with the factory system and any alterations behind the CC to the engine would effect those standard conditions, The aftermarket ones I have seen are not what I consider "true duals" since they are split behind the converter and usually behind the stock muffler, I do think they produce a louder not really pleasant sound, but I don't know about any improvement in performance or economy. After I found out the extra cost, I blew the idea off as a mere "childish dream"

Hey Gator,

It's easy for me to spend your money, so take a look here for a cool exhaust system. Dyno Proven . If your 6.0 is the same as my Yukon 6.0, they have a lot of very high performance stuff.

Thanks for the site BigBob. Did learn that 2 1/2" is the size; will contact them for prices.

"DPPI Exhaust Systems

Only T-304 stainless steel, the highest grade of stainless suitable for exhaust fabrication, is used to fabricate all pipes, mufflers, hangers and tips of each Dyno-Proven True-Dual cat-back exhaust system. Most competitive systems use the least expensive grade of stainless available.

Each muffler is designed, custom built and tuned to develop the maximum amount of power and a pleasing exterior tone. Additionally, as opposed to most competitive systems a great deal of attention has been devoted to minimizing exhaust resonance inside the vehicle. Most competitive manufacturers use the same muffler for a variety of applications, thus performance results are reduced and interior noise levels tend to be objectionable.

All DPPI exhaust system are developed on the Dyno to maximize the power output of both the Dyno-Proven CoolChargerâ„¢ and PowrPakâ„¢ systems. When installed without either the CoolChargerâ„¢ or PowrPakâ„¢ systems, many purchasers have reported a 12 … 22 horsepower increase (depending on engine size) and a 2 … 3 mile per gallon improvement in fuel mileage.


The Escalade (6.0 liter), EXT, and GMC Denali systems are all True-Dual systems featuring two 2 ½” OD pipes connected to the catalytic converters. They continue through the muffler, two 2 ¼” pipes lead from the outbound end of the muffler to the rear of the vehicle where both pipes terminate with distinctive individual 4-inch oval tips."

As a private person or an Aftermarket Supplier you can install what ever exhaust system you want on your vehicle, as loud as you want, for as long as you can get away with it. However, the Automobile Manufactures, and their "silence of the factory system" as you put it, are controlled by State and Local laws when it comes to exhaust noise emissions and they go to great lengths to keep it under control. States like New York and California and Cities like New York and Chicago have their own laws on the subject and the CEO of each car line signs an affidavit that the vehicles under his/her control are in compliance prior to releasing the vehicle for sale.

Every engine/transmission/body style combination is evaluated. Tires and engine induction systems play a big roll in the results and are evaluated also. Many car lines have more than one exhaust system supplier and they all need to be evaluated. The tests are conducted in a large open area, on a specially prepared and maintained road surface. Vehicles are driven through a 200 foot trap, locked in second gear. They enter the trap at 25 mph, accelerate at wide open throttle until the end of the trap, but not exceeding 50 mph. Microphones, set back from the path of the vehicle by 50 feet on each side, record the sound levels on precision equipment. The current (low level value) law is 80 dba I believe and in GM's case they use 78 dba as their max. value allowed. Vehicles intended for Export receive even tighter scrutiny and all certification tests are observed and validated by a third party of the Importing country's choice.

As Dubia would say, "It's a big job, We're workin hard, It's hard work."

Oldie's key words are In Texas metro areas (Idon't live in one) do emmissions testing, and the politicos look with disdane on "modified" exhaust systems so Inspection stations, run you thru the gauntlet in the metro areas. They also look upon Good ole boys in loud pickups and carsfrom the boonies even rice burners making much noise from the tailpipes, it is caused excessive noise ticket and costs as much as a good muffler replacement. Our old antiques don't have to have that annual inspection so we rumble along, hopeing the Smokey bear or the state Trooper is busy eating some Krusty Kreemes..

In this area the exhaust shops will not alter any stock exhaust system.Due to federal emission rules its illegal.

If Chevrolet could add some exhaust modifications and increase the power 20 % and deliver another 2 MPG it would already be on your truck.

With the exhaust passing thru the cat. converter you will never get a nice tone out of it.

Save our money.You have a great stainless steel system that will last for the life of the truck.

Good advice Gene, It has been an engineering nightmare ever since the Feds got into the engineering mandate business, maybe it was necessary. There is nothing more perplexing to me than to have to engineer an automobile based upon what chemically desirable gasseous mixture comes out of the tailpipe rather than the torque and Horsepower that comes out of the driveshaft at the most economical rate.

Gene & Mr. Mack,

Sounds like good advise to me. I'm sure there is a formula for compression power conversion.
The exhaust would be part of this formula.

The speed builders who designed and machined my engine used oversized valves double sprung to prevent floating.

The exhaust gasses must exit quickly after they have converted to power.

Camshaft timing and crankshaft stroke are part of the formula.

A change in any one will throw off the formula.

MM is correct; that the EPA is not in the engine design business.