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Fever for the Flava
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444 Posts
Discussion Starter #1
would a 3 inch straight exhaust be good with a 4.3 carb s-10 with headers and a 40 series flowmaster?:dunno:
 

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ZQ8 Sonoma Owner
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91 Posts
Too big unless your blown or turboed. 2.5" exhaust is the best up to 250HP. Anything bigger, and you will be losing too much backpressure.


Greg G.
 

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Fever for the Flava
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444 Posts
Discussion Starter #3
thank, i had heard something about back backpressure, but i wasnt sure
 

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1,329 Posts
Don't listen to that about a 3 inch system. Yes torque doesnt improve with a 3inch, but doesnt dropp either. I run a custom ( By the way thats the way to go, for your other post) system, it consists of JBA headers, 2 inch down pipes that join to a 3 inch pipe, random tech cat, 3 inch mid pipe , Dynomax Super and down turn. I make more torque than I did before and upper rpm horsepower even more than the 2 1/2 would. I had a 2 1/2 cat back prior, the headers added the torque in low end.
 

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Fever for the Flava
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444 Posts
Discussion Starter #5
would i be doing better with straight pipes or a cat-back
 

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Straight pipes reduce almost all back pressure and our cams, injection, computer etc. rely on at least some. Cat back!
 

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Fever for the Flava
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444 Posts
Discussion Starter #7
would it be alright if i just weld the stock cat to the 3" pipe
 

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ZQ8 Sonoma Owner
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91 Posts
I still wouldnt go 3" unless I was making over 250HP. Youre not blown or injected, so id keep it at 2.5". Its your choice, but I think you would be happier with the 2.5 piping.



Greg G.
 

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2 Litre Terror
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1,964 Posts
Im with Greg on this one. In an article from This months truckin', a reader had a similar question. The 4.3's exhaust ports and the way they are laid out make this motor like lots of velocity over volume. Just a point here. You can make all the claims you want about more torque (see above post) but that doesnt mean that your making the most torque you can. Sure it sounds impressive to say that you have a 3 inch exhaust but its like havin a 9 inch D***, if you dont know what to do with it or the girl your with is 4'3, it dont matter how big it is. Put the truck on a dyno and see the difference. In an article from SUV magazine about 3 or 4 months ago, they saw an increase of 8 lbs/ft of torque from a 2 1/4 inch system over a 3 inch. Sure that huge pipe may be making more power in the upper RPM ranges but were do we spend 90% of our time driving?. Just some info to help.....
 

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ZQ8 Sonoma Owner
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91 Posts
Thanks 02! I think that should clarify the 3" exhaust deal. I have seen a lot of people on this board with the 3" exhaust, but no major modifications, thus hurting the torque. You had something pretty funny in your reply, I almost choked reading it


Greg G.:p
 

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Fever for the Flava
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444 Posts
Discussion Starter #11
ok thats clear a lot of things up i think ill go with a single 40 series flowmaster, with a highflow cat, and ill bend the pipe to go before the rear tire on the drivers side, and keep it hidden, and once everything is fixed up, i'll be a dual tip on it.
 
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