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Discussion Starter #1
Ok need some help here. Put the Dough Thorley TriY Ceramic coated headers I bought MONTHS ago on the truck this past weekend and had them welded up today. ( First good chance ive had to install them )
Love them so far.

OK I was talking to the exhaust guy who did not like my current setup after the headers. Loved the headers and the truck though (hes a chevy guy).

He said with the flow I got coming out of my headers Im killing it with my skinny exhaust pipes, Stock cats and single in dual out 40 delta.

So HE Suggested I do this and this is where I want yalls opinions.

He suggests I go buy Catco 2517 High flow cats 3" in/out

And 2 Single in Single out 3" in/out Flowmaster Super 40's (buddys got and single one and it sounds great)

And run the entire system True duals with that and 3" pipe.

How does that sound? I know it will be loud BUT is that TOO much flow? Will I not gain HP doing it this way?
I do want loud, BUT not at the cost of performance gain.
 

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Discussion Starter #3
Any more opinions, thats what im looking for is opinions from folk that know.

Overkill in waste of money, or overkill in to much flow and loss of backpressure= LESS performance?

Elaborate please.

Price is going to not cost me much differance between the smallest stuff and the 3" pipe stuff.


I just know he had a 350 blazer on 35's there owned by his asistant manager with he said the same setup as described above.
NO idea on the performance (a major factor for me) but as far as sound goes it sounded really meaty/throaty/loud
 

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3" is overkill IMO on your application... it may feel good on the top end, but off the line it will be sluggish.
biggest i would do is 2.5"... but i dont think those motors respond well to true duals like the older ones do... i have no exp there.
how exactly is your exhaust set up now after the headers?
 

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yeah dual 3" is TOO much for a 350 NA. the stock pipes from the manifolds to the cats is 1 7/8" dual. I am running 2 1/2" pipes from my Hooker Comps (2462-1HKR) to dual 2 1/2" Catco Cats.

The exhaust velocity will be too low with dual 3" and low rpm torque and throttle response will suffer.

Sounds like the exhaust guy has a bunch of 3" pipe he wants to use up. He is correct though, teh stock Vortec 350 headpipes(pipes that connect the manifold to teh cats) is pretty restrictive.

peace
Hog
 

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Getting new flowmasters won't help the loss of power you experienced from running your original flowmasters.
 

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Discussion Starter #11
Yea I thought the same thing that it was way to big of a pipe to run... Reason I asked.

Current. tri-Y's
into Stock Cats
Stock exhaust into the ypipe and into a single in dual out 40 delta and out the rear. I do not know the diameter of the pipes.

WOULD I BENIFIT from

2.5" Catco Cats,
2.5" Duals into
Magnaflow 2.5" X Pipe right before
2 - 2.5" Single in single out Super 40's
2.5" out the back with tips setup about like they are now.

Any Power gains over what I got now like that?

FYI.. with just adding the headers its like an entire new truck!!!
I finally have my low end back, and it cruises alot better than before. Sounds 10x better.
Would like to not go in the opposite direction on the power gains though. But getting some more power out of it in the low and still add to the high would be my idea thing. PLUS the delta is a little quiet for my liking.
 

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Discussion Starter #12

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Sweet bottom num nums
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delete the cat get an o2 sim, run a magnaflow x pipe muffler all in 2.5" where the two pipes join have him redo so that they run dual into the new muffler. that should be real nice not tooo expensive and plenty good for what you got
 

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With what you're running I would run like what olred21 said. If it were me I'd run a magnaflow xpipe with 2.5" pipes back to dual dynomax bullets.

I'm running a single bullet right now and it worked great for my stock engine but my engine feels choked now that I put my cam in.
 

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doubt a high flwo cat will differ from wht you have... stock cats flow very well IMO. try the x pipe with your current set up and see how you like that and go from there
 

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oh yea, I'm running magnaflow high flow cats and they didn't make even a tiny bit of difference from the stock ones. Save you money and spend it elsewhere
 

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Discussion Starter #17
Wheres yalls sound clips or videos of your trucks at so i can hear it? lol

So yall are saying, Keep my stock cats. 2.5" TRUE duals with Magnaflow 2.5" X
into 2 single in single out mufflers

How does dynomax bullets sound? Cant say ive heard them before.
But I do love the flow sound and my buddys super 40s are some of the best Ive ever heard.
 

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spintechs! I have bullets and like them but am definately thinking of going spintech
 

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I have read in here and FSC that the stock cats flow as much as aftermarket cats. 3" is way over kill.
 

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Stock cats are not hurting you. Stock pipes are what, 2.5" to the 2.75" Y-pipe?

Get a good 3" catback, it flows plenty for your motor. Anymore will kill VELOCITY (this is the key word here), you never want back pressure EVER.
 
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