How does the cat back system improve performance when it's still going through a single pipe into the converter and a single pipe splitting off into duals from the converter?

All of the info I find online is what is put out by the manufacturers and no real data to support it. Would I see the same results staying with my factory 2.5 inch single exhaust with a Flowmaster muffler? Other than looking like dual exhaust, is there really a benefit?

 

A cat back will flow more than your stock exhaust system, that is why you will make more power. Its a modest increase, but an increase nonetheless

My motor is all stock with a BB mail order tune so i just cut out the stock muffler and replaced it with a higher flowing muffler. My butt dyno showed an increase in power across the entire RPM range

 

Have you ever lifted a stock muffler from one of these trucks? The damn thing weighs an easy 60-70lbs and is not a straight through design.

if you want improved flow at minimal cost, replace the stocker with something free flowing, like MagnaFlow or Dynomax.

 

That's where I am now with everything stock. I've changed out a few mufflers in my life but it's been ages and with the tighter emission standards I'm guessing they're pretty restrictive. I was just curious how much better it would breathe because of 2 tailpipes instead of one. I know true duals would open it up and help a lot but I don't know how they would affect my computer.

I've ordered a Spectre CAI and a throttle body spacer that will be here later this week. I have a couple of guys that I've met through some of the cruises that build race cars and can retune the computer for me for a fair price. There are a lot of things I want to do to the truck but have limited funds so I want to take care of what will benefit me the most.

 

Return the TB spacer, they are worthless unless you are going to spray NOS. This isnt a an old carb'd motor where a spacer could do some good. It's just another spot for a possible vacuum leak if you ask me.

Factory muffler is heavy and doesnt flow awesome but the factory catback aside from the muffler will flow just fine. The pipe is 2.75in and takes a bit to outflow it, switching to a true dual on a stockish setup is not worth the cost and no real gains could be had.

 

I am a 2000 Street Truck ECSB 1500 4x4 data point.

A 5.3 powered COPO Z71 in total street trim. A large heavy truck by measure and admittedly horribly under powered, but with reasonable capability on tap..

A summary of the fruits these parts, (that I went with my gut on), based on a lot of research data analysis time spent here at PTT.Net....and 35 years of FAA supervised Air Safety Responsibility...

I'd be happy to relate what my realistic expectations were, What I got and what capabilities just aren't in the cards on a 1500 N/A driver.

Anybody wanna learn some things about these "Heavier 1500's?"

And I'm collecting the parts necessary to convert to a double adjustable coil over. Waiting on shocks and springs.

 

I've done some research on the spacers and from what I've found, there are as many who see a difference in gas mileage and performance as there are who don't. The consensus seems to be that the more stock everything is, the more of a difference it can make. If you've already made mods to increase performance, you'll probably not see a difference.

 

Point of the spacer is to speedair up slightly, CAI theoretically does that anyway, faster colder air better atomization, the CAI makes the spacer pointless, and a PITA if you are cable driven...... The 2-3 hp and maybe .5 mpg arent really worth it..... As previously stated it is a source for vacuum leak to be added.... Ifyou have clutch fan setup, the intake tube is damnnear on the shroud anyway now add spacer and youre talking about having to cut the shroudto clear it!!!!

 

Back to original question, reverts to another thread we were discussing, more in more out, catbacks even if its a single in/out flow much better simply due to less restriction inthe muffler itself!!! When I had 2013 4.8 silverado i got a hella deal on a flowmaster 40series, so i cut the stock muffler off and put the 40 in its place and wasnt a vast improvement, by any means, however there was a differemce in butt dyno and fuel mileage.... And it sounded good!!!

 

And it all comes down to what you want to put into it. I'm no engineer but every bend and turn and bump in the pipe subtly changes how the engine runs. That's why the high dollar systems are so high dollar; engineers, dynos, test tracks,...it's the R&D. Just cutting a muffler off isn't always better like the old days