New idea for exhaust setup: Catback & Deleted 3rd cat, true 3"

[FL335i]

I spent some time today looking at all the bolt on cat-backs. 3" Mandrel bent seems to be the norm. What I did notice is most of them, all but corsa do not have a flex pipe. They all rigidly bolt up. Look at the pics, it's clear they have some kind of small diameter pipe and then if expands out to 3". So the Cat-back is 3" mandrel, but whatever it's hooking to, the 3rd cat, is not 3" on the outlet. On the inlet side of the cat the Y pipe looks like 3" all day long where the two banks come together. My plan of attack is get a AFE cat-back and then have a muffler shop cut the 3rd cat out and install a short flex spool like the OEM, but in 3". My thoughts are weld a 3" flange on the Y-pipe upstream of the 3rd cat. And then cut off the few inches of 2.5" or whatever all these cat-backs are starting off with and put a true 3" flange on it. So the idea is put a flex spool between those two flanges for a OEM fitment and vibration. And then we have the stock y pipe coming to the stock 3" and then we flange into the 3" Flex pipe and flange into the 3" cat-back system. That 3rd cat really necks down on the outlet side. Thus far, the AFE system is top of my list. AFE or maybe the Dynomax. Both are simple, 3" and I'm going to cut the connection section off and weld a 3" flange on it anyway... why spend big bucks. This setup should be spot on the money. And no check engine lights would come on.

 

 

Flex Pipe: http://www.jegs.com/i/JEGS+Performance+Products/555/30777/10002/-1

 

Flanges: http://www.jegs.com/i/Hedman/500/21118/10002/-1

OR, for a more stock look these connectors: http://www.jegs.com/i/Flowmaster/389/15930/10002/-1

 

AFE Cat-back system: http://afepower.com/shop/details_new.php?partno=49-44038-B&filter&menu=gas&engine=5.3L&searchtype=vehicle&make=Chevrolet Truck&model=Silverado&year=2014&engine=5.3L&&brandID=63

 

 

And if done properly, will look pretty much stock. Stealth is good. Shouldn't be obnoxious loud, will function perfect and not squeak every time the truck goes between 4cyl mode like my mine does. Squeak, squeak,... I hear that valve when I have the windows down. Not cool.

[07Softail]

Actually at the merge point of the Stock Y-pipe is 3 1/2" I measured it and whacked the 3rd cat off and bought a 3 1/2 ball connector from Dr.Gas and connected it to the 3 1/2 inch MBRP S5086409 6.2 exhaust on my 5.3. If i wanted to install my stock exhaust to the Y-Pipe it would bolt right back together without the 3rd cat of course. The Dealer Tech saw this and was like Damn... (He didn't notice it) until I showed it to him. You don't need the flex pipe crap no squeaking here.

 

RT

[Conky Conky]

Check out my truck on you tube its 2013 5.3 chevy extended cab short box. I got 2 3/4 inch cat back straight pipe no 3rd cat and 3.5 inch crime tips on 90s. It sounds like a big old cammed up big block while idleing. My you tube channel is Conky Conky

[FL335i]

^07softtail- So I could buy a set of Dr. Gas 3.5" Ball/sockets and then cut the 3rd cat off, weld it right to the 3.5" section of Y pipe and then adapt it to a 3" or 3.5" Exhaust system. I like it. Done deal. just not sure a 3.5" is really needed. Did you lose any low-end torque? The MBRP muffler looks small, figured it's louder than most cat-backs, correct?

[07Softail]

That's correct... I figured it would feel soft on the bottom but I can't really tell. I am doing a tune soon and I will see then if it lost any. I also emailed DR Gas and they told me you could use a 3.5" ball end to a 3" flange end so in simple terms that would be your pipe reduction point as long as the angle stays fairly straight. It sounds good to me and will bark when you hit the loud peddle!

 

RT

[07Softail]

I did the 3.5" exhaust with the idea of doing ARH long tube header and Y-pipe so when I do it will bolt up just like a stock system would.

 

RT

[FL335i]

^I'm liking it, but will do the 3" system. Maybe AFE. But I knew there was something goofy going on with that 3rd cat area. Looks like it left a lot on the table. That's the squeeze point in the system.

[FL335i]

Ok, on the fence between AFE and magnaflow. AFE's is considerably cheaper. The only difference I think is magnaflow's has a flex section up front. ??? Opinions? Plan is do the cat-back then in the future, delete the 3rd cat. That's as far as I'm going.

[07Softail]

You don't need the flex section if you are concerned about that....and as far as the 3rd cat you can drill it out and break it appart to remove the material It's very brittle and can be removed very easy. It took me 15-20 miniutes to drill and dig it out.

 

RT

[FL335i]

^ Hollowing it out is OK with me, but I wonder what size the inlet/outlet on it is. I want a true 3" or 3.5" flange on the Y-pipe and then get it down to true 3" into the cat-back. So I might have to cut off the front small section on the cat-back. They all seem to have small pipe and then flare out to 3".

[07Softail]

it's not even 3" it's more like 2 3/4 exiting the cat and at the cat-back connection but the pipe section before it goes into the cat is 3.5". If you want a full 3" you will have to do what we discussed in the earlier post with the ball connector. Trust me I've done all the homework for you! LOL!!!!

 

RT

[FL335i]

^Yes you have. I think a 3.5" ball connector with a AFE cat-back is the way to go.

[Conky Conky]

These trucks also sound very good with just taking off the factory muffler and going 3.5 inch from the 3rd cat back out on 45degree angle and 4.5 inch crome tip.O and FYI if your interest I found away to completey disconnect traction control.